diff --git a/bin/df/df.c b/bin/df/df.c
index 5420da92500e..f48c8c95e841 100644
--- a/bin/df/df.c
+++ b/bin/df/df.c
@@ -131,14 +131,14 @@ main(int argc, char *argv[])
 			 */
 			if (kflag)
 				break;
-			putenv("BLOCKSIZE=512");
+			setenv("BLOCKSIZE", "512", 1);
 			hflag = 0;
 			break;
 		case 'c':
 			cflag = 1;
 			break;
 		case 'g':
-			putenv("BLOCKSIZE=1g");
+			setenv("BLOCKSIZE", "1g", 1);
 			hflag = 0;
 			break;
 		case 'H':
@@ -152,7 +152,7 @@ main(int argc, char *argv[])
 			break;
 		case 'k':
 			kflag++;
-			putenv("BLOCKSIZE=1024");
+			setenv("BLOCKSIZE", "1024", 1);
 			hflag = 0;
 			break;
 		case 'l':
@@ -162,7 +162,7 @@ main(int argc, char *argv[])
 			lflag = 1;
 			break;
 		case 'm':
-			putenv("BLOCKSIZE=1m");
+			setenv("BLOCKSIZE", "1m", 1);
 			hflag = 0;
 			break;
 		case 'n':
diff --git a/bin/sh/var.c b/bin/sh/var.c
index 54a0a84080c3..afb3c862e653 100644
--- a/bin/sh/var.c
+++ b/bin/sh/var.c
@@ -289,6 +289,7 @@ void
 setvareq(char *s, int flags)
 {
 	struct var *vp, **vpp;
+	char *p;
 	int len;
 
 	if (aflag)
@@ -319,7 +320,10 @@ setvareq(char *s, int flags)
 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
 				chkmail(1);
 			if ((vp->flags & VEXPORT) && localevar(s)) {
-				putenv(s);
+				p = strchr(s, '=');
+				*p = '\0';
+				(void) setenv(s, p + 1, 1);
+				*p = '=';
 				(void) setlocale(LC_ALL, "");
 			}
 			INTON;
@@ -335,7 +339,10 @@ setvareq(char *s, int flags)
 	INTOFF;
 	*vpp = vp;
 	if ((vp->flags & VEXPORT) && localevar(s)) {
-		putenv(s);
+		p = strchr(s, '=');
+		*p = '\0';
+		(void) setenv(s, p + 1, 1);
+		*p = '=';
 		(void) setlocale(LC_ALL, "");
 	}
 	INTON;
@@ -596,7 +603,10 @@ exportcmd(int argc, char **argv)
 
 						vp->flags |= flag;
 						if ((vp->flags & VEXPORT) && localevar(vp->text)) {
-							putenv(vp->text);
+							p = strchr(vp->text, '=');
+							*p = '\0';
+							(void) setenv(vp->text, p + 1, 1);
+							*p = '=';
 							(void) setlocale(LC_ALL, "");
 						}
 						goto found;
diff --git a/include/stdlib.h b/include/stdlib.h
index 98fe8b7756c6..98cb465c8f33 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -161,7 +161,7 @@ void	 _Exit(int) __dead2;
 int	 posix_memalign(void **, size_t, size_t); /* (ADV) */
 int	 rand_r(unsigned *);			/* (TSF) */
 int	 setenv(const char *, const char *, int);
-void	 unsetenv(const char *);
+int	 unsetenv(const char *);
 #endif
 
 /*
@@ -197,7 +197,7 @@ long	 mrand48(void);
 long	 nrand48(unsigned short[3]);
 int	 posix_openpt(int);
 char	*ptsname(int);
-int	 putenv(const char *);
+int	 putenv(char *);
 long	 random(void);
 char	*realpath(const char *, char resolved_path[]);
 unsigned short
diff --git a/lib/libc/stdlib/Makefile.inc b/lib/libc/stdlib/Makefile.inc
index 99ea7fb20ff3..f9b8fec7ab9d 100644
--- a/lib/libc/stdlib/Makefile.inc
+++ b/lib/libc/stdlib/Makefile.inc
@@ -8,10 +8,10 @@ MISRCS+=_Exit.c a64l.c abort.c abs.c atexit.c atof.c atoi.c atol.c atoll.c \
 	bsearch.c div.c exit.c getenv.c getopt.c getopt_long.c \
 	getsubopt.c grantpt.c hcreate.c heapsort.c imaxabs.c imaxdiv.c \
 	insque.c l64a.c labs.c ldiv.c llabs.c lldiv.c lsearch.c malloc.c \
-	merge.c putenv.c qsort.c qsort_r.c radixsort.c rand.c random.c \
-	reallocf.c realpath.c remque.c setenv.c strfmon.c strtoimax.c \
-	strtol.c strtoll.c strtoq.c strtoul.c strtonum.c strtoull.c strtoumax.c \
-	strtouq.c system.c tdelete.c tfind.c tsearch.c twalk.c
+	merge.c qsort.c qsort_r.c radixsort.c rand.c random.c \
+	reallocf.c realpath.c remque.c strfmon.c strtoimax.c \
+	strtol.c strtoll.c strtoq.c strtoul.c strtonum.c strtoull.c \
+        strtoumax.c strtouq.c system.c tdelete.c tfind.c tsearch.c twalk.c
 
 SYM_MAPS+= ${.CURDIR}/stdlib/Symbol.map
 
diff --git a/lib/libc/stdlib/getenv.3 b/lib/libc/stdlib/getenv.3
index 3d365f16a26b..33d9c36f3a79 100644
--- a/lib/libc/stdlib/getenv.3
+++ b/lib/libc/stdlib/getenv.3
@@ -32,7 +32,7 @@
 .\"     @(#)getenv.3	8.2 (Berkeley) 12/11/93
 .\" $FreeBSD$
 .\"
-.Dd October 12, 2006
+.Dd June 20, 2007
 .Dt GETENV 3
 .Os
 .Sh NAME
@@ -50,22 +50,13 @@
 .Ft int
 .Fn setenv "const char *name" "const char *value" "int overwrite"
 .Ft int
-.Fn putenv "const char *string"
-.Ft void
+.Fn putenv "char *string"
+.Ft int
 .Fn unsetenv "const char *name"
 .Sh DESCRIPTION
 These functions set, unset and fetch environment variables from the
 host
 .Em environment list .
-For compatibility with differing environment conventions,
-the given arguments
-.Fa name
-and
-.Fa value
-may be appended and prepended,
-respectively,
-with an equal sign
-.Dq Li \&= .
 .Pp
 The
 .Fn getenv
@@ -97,11 +88,18 @@ to the given
 .Pp
 The
 .Fn putenv
-function takes an argument of the form ``name=value'' and is
-equivalent to:
-.Bd -literal -offset indent
-setenv(name, value, 1);
-.Ed
+function takes an argument of the form ``name=value'' and
+puts it directly into the current environment,
+so altering the argument shall change the environment.
+If the variable
+.Fa name
+does not exist in the list,
+it is inserted with the given
+.Fa value .
+If the variable
+.Fa name
+does exist, it is reset to the given
+.Fa value .
 .Pp
 The
 .Fn unsetenv
@@ -121,15 +119,55 @@ is not in the current environment,
 .Dv NULL
 is returned.
 .Pp
-.Rv -std setenv putenv
+.Rv -std setenv putenv unsetenv
 .Sh ERRORS
 .Bl -tag -width Er
+.It Bq Er EINVAL
+The function
+.Fn getenv ,
+.Fn setenv
+or
+.Fn unsetenv
+failed because the
+.Fa name
+is a
+.Dv NULL
+pointer, points to an empty string, or points to a string containing an
+.Dq Li \&=
+character.
+.Pp
+The function
+.Fn putenv
+failed because
+.Fa string
+is a
+.Dv NULL
+pointer,
+.Fa string is without an
+.Dq Li \&=
+character or
+.Dq Li \&=
+is the first character in
+.Fa string .
+This does not follow the
+.Tn POSIX
+specification.
 .It Bq Er ENOMEM
 The function
-.Fn setenv
+.Fn setenv ,
+.Fn unsetenv
 or
 .Fn putenv
 failed because they were unable to allocate memory for the environment.
+.It Bq Er EFAULT
+The functions
+.Fn setenv ,
+.Fn unsetenv
+or
+.Fn putenv
+failed to make a valid copy of the environment due to the environment being
+corrupt (i.e., a name without a value).  A warning will be output to stderr with
+information about the issue.
 .El
 .Sh SEE ALSO
 .Xr csh 1 ,
@@ -141,6 +179,13 @@ The
 .Fn getenv
 function conforms to
 .St -isoC .
+The
+.Fn setenv ,
+.Fn putenv
+and
+.Fn unsetenv
+functions conforms to
+.St -p1003.1-2001 .
 .Sh HISTORY
 The functions
 .Fn setenv
@@ -152,19 +197,30 @@ The
 .Fn putenv
 function appeared in
 .Bx 4.3 Reno .
+.Pp
+Until
+.Fx 7.0 ,
+.Fn putenv
+would make a copy of 
+.Fa string
+and insert it into the environment using
+.Fn setenv .
+This was changed to use
+.Fa string
+as the memory location of the ``name=value'' pair to follow the
+.Tn POSIX
+specification.
 .Sh BUGS
 Successive calls to
 .Fn setenv
-or
-.Fn putenv
-assigning a differently sized
+that assign a larger-sized
 .Fa value
-to the same
+than any previous value to the same
 .Fa name
 will result in a memory leak.
 The
 .Fx
-semantics for these functions
+semantics for this function
 (namely, that the contents of
 .Fa value
 are copied and that old values remain accessible indefinitely) make this
diff --git a/lib/libc/stdlib/getenv.c b/lib/libc/stdlib/getenv.c
index 306b6a19f8be..5f6f49797362 100644
--- a/lib/libc/stdlib/getenv.c
+++ b/lib/libc/stdlib/getenv.c
@@ -1,89 +1,568 @@
-/*
- * Copyright (c) 1987, 1993
- *	The Regents of the University of California.  All rights reserved.
+/*-
+ * Copyright (c) 2007 Sean C. Farley <scf@FreeBSD.org>
+ * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
+ *    notice, this list of conditions and the following disclaimer,
+ *    without modification, immediately at the beginning of the file.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+#include <sys/types.h>
+#include <err.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
 
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)getenv.c	8.1 (Berkeley) 6/4/93";
-#endif /* LIBC_SCCS and not lint */
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
-#include <stdlib.h>
-#include <stddef.h>
-#include <string.h>
-
-inline char *__findenv(const char *, int *);
 
 /*
- * __findenv --
- *	Returns pointer to value associated with name, if any, else NULL.
- *	Sets offset to be the offset of the name/value combination in the
- *	environmental array, for use by setenv(3) and unsetenv(3).
- *	Explicitly removes '=' in argument name.
+ * Standard environ.  environ variable is exposed to entire process.
  *
- *	This routine *should* be a static; don't use it.
+ *	origEnviron:	Upon cleanup on unloading of library or failure, this
+ *			allows environ to return to as it was before.
+ *	environSize:	Number of variables environ can hold.  Can only
+ *			increase.
  */
-inline char *
-__findenv(name, offset)
-	const char *name;
-	int *offset;
-{
-	extern char **environ;
-	int len, i;
-	const char *np;
-	char **p, *cp;
+extern char **environ;
+static char **origEnviron;
+static int environSize = 0;
 
-	if (name == NULL || environ == NULL)
-		return (NULL);
-	for (np = name; *np && *np != '='; ++np)
-		continue;
-	len = np - name;
-	for (p = environ; (cp = *p) != NULL; ++p) {
-		for (np = name, i = len; i && *cp; i--)
-			if (*cp++ != *np++)
-				break;
-		if (i == 0 && *cp++ == '=') {
-			*offset = p - environ;
-			return (cp);
+/*
+ * Array of environment variables built from environ.  Each element records:
+ *	name:		Pointer to name=value string
+ *	name length:	Length of name not counting '=' character
+ *	value:		Pointer to value within same string as name
+ *	value size:	Size (not length) of space for value not counting the
+ *			nul character
+ *	active state:	true/false value to signify whether variable is active.
+ *			Useful since multiple variables with the same name can
+ *			co-exist.  At most, one variable can be active at any
+ *			one time.
+ *	putenv:		Created from putenv() call.  This memory must not be
+ *			reused.
+ */
+static struct envVars {
+	size_t nameLen;
+	size_t valueSize;
+	char *name;
+	char *value;
+	bool active;
+	bool putenv;
+} *envVars = NULL;
+
+/*
+ * Environment array information.
+ *
+ *	envActive:	Number of active variables in array.
+ *	envVarsSize:	Size of array.
+ *	envVarsTotal:	Number of total variables in array (active or not).
+ */
+static int envActive = 0;
+static int envVarsSize = 0;
+static int envVarsTotal = 0;
+
+
+/* Deinitialization of new environment. */
+static void __attribute__ ((destructor)) __clean_env(void);
+
+
+/*
+ * Inline strlen() for performance.  Also, perform check for an equals sign.
+ * Cheaper here than peforming a strchr() later.
+ */
+static inline size_t
+__strleneq(const char *str)
+{
+	const char *s;
+
+	for (s = str; *s != '\0'; ++s)
+		if (*s == '=')
+			return (0);
+
+	return (s - str);
+}
+
+
+/*
+ * Comparison of an environment name=value to a name.
+ */
+static inline bool
+strncmpeq(const char *nameValue, const char *name, size_t nameLen)
+{
+	if (strncmp(nameValue, name, nameLen) == 0 && nameValue[nameLen] == '=')
+		return (true);
+
+	return (false);
+}
+
+
+/*
+ * Using environment, returns pointer to value associated with name, if any,
+ * else NULL.  If the onlyActive flag is set to true, only variables that are
+ * active are returned else all are.
+ */
+static inline char *
+__findenv(const char *name, size_t nameLen, int *envNdx, bool onlyActive)
+{
+	int ndx;
+
+	/*
+	 * Find environment variable from end of array (more likely to be
+	 * active).  A variable created by putenv is always active or it is not
+	 * tracked in the array.
+	 */
+	for (ndx = *envNdx; ndx >= 0; ndx--)
+		if (envVars[ndx].putenv) {
+			if (strncmpeq(envVars[ndx].name, name, nameLen)) {
+				*envNdx = ndx;
+				return (envVars[ndx].name + nameLen +
+				    sizeof ("=") - 1);
+			}
+		} else if ((!onlyActive || envVars[ndx].active) &&
+		    (envVars[ndx].nameLen == nameLen &&
+		    strncmpeq(envVars[ndx].name, name, nameLen))) {
+			*envNdx = ndx;
+			return (envVars[ndx].value);
 		}
-	}
+
 	return (NULL);
 }
 
+
 /*
- * getenv --
- *	Returns ptr to value associated with name, if any, else NULL.
+ * Using environ, returns pointer to value associated with name, if any, else
+ * NULL.  Used on the original environ passed into the program.
+ */
+static char *
+__findenv_environ(const char *name, size_t nameLen)
+{
+	int envNdx;
+
+	/* Check for non-existant environment. */
+	if (environ == NULL)
+		return (NULL);
+
+	/* Find variable within environ. */
+	for (envNdx = 0; environ[envNdx] != NULL; envNdx++)
+		if (strncmpeq(environ[envNdx], name, nameLen))
+			return (&(environ[envNdx][nameLen + sizeof("=") - 1]));
+
+	return (NULL);
+}
+
+
+/*
+ * Using the environment, rebuild the environ array for use by other C library
+ * calls that depend upon it.
+ */
+static int
+__rebuild_environ(int newEnvironSize)
+{
+	char **tmpEnviron;
+	int envNdx;
+	int environNdx;
+	int tmpEnvironSize;
+
+	/* Resize environ. */
+	if (newEnvironSize > environSize) {
+		tmpEnvironSize = newEnvironSize * 2;
+		tmpEnviron = realloc(environ, sizeof (*environ) *
+		    (tmpEnvironSize + 1));
+		if (tmpEnviron == NULL)
+			return (-1);
+		environSize = tmpEnvironSize;
+		environ = tmpEnviron;
+	}
+	envActive = newEnvironSize;
+
+	/* Assign active variables to environ. */
+	for (envNdx = envVarsTotal - 1, environNdx = 0; envNdx >= 0; envNdx--)
+		if (envVars[envNdx].active)
+			environ[environNdx++] = envVars[envNdx].name;
+	environ[environNdx] = NULL;
+
+	return (0);
+}
+
+
+/*
+ * Enlarge new environment.
+ */
+static inline bool
+__enlarge_env(void)
+{
+	int newEnvVarsSize;
+	struct envVars *tmpEnvVars;
+
+	envVarsTotal++;
+	if (envVarsTotal > envVarsSize) {
+		newEnvVarsSize = envVarsTotal * 2;
+		tmpEnvVars = realloc(envVars, sizeof (*envVars) *
+		    newEnvVarsSize);
+		if (tmpEnvVars == NULL) {
+			envVarsTotal--;
+			return (false);
+		}
+		envVarsSize = newEnvVarsSize;
+		envVars = tmpEnvVars;
+	}
+
+	return (true);
+}
+
+
+/*
+ * Using environ, build an environment for use by standard C library calls.
+ */
+static int
+__build_env(void)
+{
+	char **env;
+	int activeNdx;
+	int envNdx;
+	int rtrnVal;
+	int savedErrno;
+	size_t nameLen;
+
+	/* Check for non-existant environment. */
+	if (environ == NULL)
+		return (0);
+	if (environ[0] == NULL)
+		goto SaveEnviron;
+
+	/* Count environment variables. */
+	for (env = environ, envVarsTotal = 0; *env != NULL; env++)
+		envVarsTotal++;
+	envVarsSize = envVarsTotal * 2;
+
+	/* Create new environment. */
+	envVars = calloc(1, sizeof (*envVars) * envVarsSize);
+	if (envVars == NULL)
+		goto Failure;
+
+	/* Copy environ values and keep track of them. */
+	for (envNdx = envVarsTotal - 1; envNdx >= 0; envNdx--) {
+		envVars[envNdx].putenv = false;
+		envVars[envNdx].name =
+		    strdup(environ[envVarsTotal - envNdx - 1]);
+		if (envVars[envNdx].name == NULL)
+			goto Failure;
+		envVars[envNdx].value = strchr(envVars[envNdx].name, '=');
+		if (envVars[envNdx].value != NULL) {
+			envVars[envNdx].value++;
+			envVars[envNdx].valueSize =
+			    strlen(envVars[envNdx].value);
+		} else {
+			warnx("environment corrupt; missing value for %s",
+			    envVars[envNdx].name);
+			errno = EFAULT;
+			goto Failure;
+		}
+
+		/*
+		 * Find most current version of variable to make active.  This
+		 * will prevent multiple active variables from being created
+		 * during this initialization phase.
+		 */
+		nameLen = envVars[envNdx].value - envVars[envNdx].name - 1;
+		envVars[envNdx].nameLen = nameLen;
+		activeNdx = envVarsTotal - 1;
+		if (__findenv(envVars[envNdx].name, nameLen, &activeNdx,
+		    false) == NULL) {
+			warnx("environment corrupt; unable to find %.*s",
+			    nameLen, envVars[envNdx].name);
+			errno = EFAULT;
+			goto Failure;
+		}
+		envVars[activeNdx].active = true;
+	}
+
+	/* Create a new environ. */
+SaveEnviron:
+	origEnviron = environ;
+	environ = NULL;
+	if (envVarsTotal > 0) {
+		rtrnVal = __rebuild_environ(envVarsTotal);
+		if (rtrnVal == -1) {
+			savedErrno = errno;
+			__clean_env();
+			errno = savedErrno;
+		}
+	} else
+		rtrnVal = 0;
+
+	return (rtrnVal);
+
+Failure:
+	savedErrno = errno;
+	__clean_env();
+	errno = savedErrno;
+
+	return (-1);
+}
+
+
+/*
+ * Remove variable added by putenv() from variable tracking array.
+ */
+static void
+__remove_putenv(int envNdx)
+{
+	memmove(&(envVars[envNdx]), &(envVars[envNdx + 1]),
+	    (envVarsTotal - envNdx) * sizeof (*envVars));
+	envVarsTotal--;
+
+	return;
+}
+
+
+/*
+ * Deallocate the environment built from environ as well as environ then set
+ * both to NULL.  Eases debugging of memory leaks.
+ */
+static void
+__clean_env(void)
+{
+	int envNdx;
+
+	/* Deallocate environment and environ if created by *env(). */
+	if (envVars != NULL) {
+		for (envNdx = 0; envNdx < envVarsTotal; envNdx++)
+			if (!envVars[envNdx].putenv)
+				free(envVars[envNdx].name);
+		free(envVars);
+		envVars = NULL;
+
+		/* Restore original environ. */
+		if (origEnviron != NULL) {
+			free(environ);
+			environ = origEnviron;
+		}
+	}
+
+	return;
+}
+
+
+/*
+ * Returns the value of a variable or NULL if none are found.
  */
 char *
-getenv(name)
-	const char *name;
+getenv(const char *name)
 {
-	int offset;
+	int envNdx;
+	size_t nameLen;
 
-	return (__findenv(name, &offset));
+	/* Check for malformed name. */
+	if (name == NULL || (nameLen = __strleneq(name)) == 0) {
+		errno = EINVAL;
+		return (NULL);
+	}
+
+	/* Find environment variable via environ or rebuilt environment. */
+	if (envVars == NULL)
+		return (__findenv_environ(name, nameLen));
+	else {
+		envNdx = envVarsTotal - 1;
+		return (__findenv(name, nameLen, &envNdx, true));
+	}
+}
+
+
+/*
+ * Set the value of a variable.  Older settings are labeled as inactive.  If an
+ * older setting has enough room to store the new value, it will be reused.  No
+ * previous variables are ever freed here to avoid causing a segmentation fault
+ * in a user's code.
+ */
+int
+setenv(const char *name, const char *value, int overwrite)
+{
+	bool reuse;
+	char *env;
+	int envNdx;
+	int newEnvActive;
+	size_t nameLen;
+	size_t valueLen;
+
+	/* Check for malformed name. */
+	if (name == NULL || (nameLen = __strleneq(name)) == 0) {
+		errno = EINVAL;
+		return (-1);
+	}
+
+	/* Initialize environment. */
+	if (envVars == NULL && __build_env() == -1)
+		return (-1);
+
+	/* Find existing environment variable large enough to use. */
+	envNdx = envVarsTotal - 1;
+	newEnvActive = envActive;
+	valueLen = strlen(value);
+	reuse = false;
+	if (__findenv(name, nameLen, &envNdx, false) != NULL) {
+		/* Deactivate entry if overwrite is allowed. */
+		if (envVars[envNdx].active) {
+			if (overwrite == 0)
+				return (0);
+			envVars[envNdx].active = false;
+			newEnvActive--;
+		}
+
+		/* putenv() created variable cannot be reused. */
+		if (envVars[envNdx].putenv)
+			__remove_putenv(envNdx);
+
+		/* Entry is large enough to reuse. */
+		else if (envVars[envNdx].valueSize >= valueLen)
+			reuse = true;
+
+	}
+
+	/* Create new variable if none was found of sufficient size. */
+	if (! reuse) {
+		/* Enlarge environment. */
+		envNdx = envVarsTotal;
+		if (!__enlarge_env())
+			return (-1);
+
+		/* Create environment entry. */
+		envVars[envNdx].name = malloc(nameLen + sizeof ("=") +
+		    valueLen);
+		if (envVars[envNdx].name == NULL) {
+			envVarsTotal--;
+			return (-1);
+		}
+		envVars[envNdx].nameLen = nameLen;
+		envVars[envNdx].valueSize = valueLen;
+
+		/* Save name of name/value pair. */
+		env = stpcpy(envVars[envNdx].name, name);
+		if ((envVars[envNdx].name)[nameLen] != '=')
+			env = stpcpy(env, "=");
+	}
+	else
+		env = envVars[envNdx].value;
+
+	/* Save value of name/value pair. */
+	strcpy(env, value);
+	envVars[envNdx].value = env;
+	envVars[envNdx].active = true;
+	newEnvActive++;
+
+	/* No need to rebuild environ if the variable was reused. */
+	if (reuse)
+		return (0);
+	else
+		return (__rebuild_environ(newEnvActive));
+}
+
+
+/*
+ * Insert a "name=value" string into then environment.  Special settings must be
+ * made to keep setenv() from reusing this memory block and unsetenv() from
+ * allowing it to be tracked.
+ */
+int
+putenv(char *string)
+{
+	char *equals;
+	int envNdx;
+	int newEnvActive;
+	size_t nameLen;
+
+	/* Check for malformed argument. */
+	if (string == NULL || (equals = strchr(string, '=')) == NULL ||
+	    (nameLen = equals - string) == 0) {
+		errno = EINVAL;
+		return (-1);
+	}
+
+	/* Initialize environment. */
+	if (envVars == NULL && __build_env() == -1)
+		return (-1);
+
+	/* Deactivate previous environment variable. */
+	envNdx = envVarsTotal - 1;
+	newEnvActive = envActive;
+	if (__findenv(string, nameLen, &envNdx, true) != NULL) {
+		/* Reuse previous putenv slot. */
+		if (envVars[envNdx].putenv) {
+			envVars[envNdx].name = string;
+			return (__rebuild_environ(envActive));
+		} else {
+			newEnvActive--;
+			envVars[envNdx].active = false;
+		}
+	}
+
+	/* Enlarge environment. */
+	envNdx = envVarsTotal;
+	if (!__enlarge_env())
+		return (-1);
+
+	/* Create environment entry. */
+	envVars[envNdx].name = string;
+	envVars[envNdx].nameLen = -1;
+	envVars[envNdx].value = NULL;
+	envVars[envNdx].valueSize = -1;
+	envVars[envNdx].putenv = true;
+	envVars[envNdx].active = true;
+	newEnvActive++;
+
+	return (__rebuild_environ(newEnvActive));
+}
+
+
+/*
+ * Unset variable with the same name by flagging it as inactive.  No variable is
+ * ever freed.
+ */
+int
+unsetenv(const char *name)
+{
+	int envNdx;
+	size_t nameLen;
+
+	/* Check for malformed name. */
+	if (name == NULL || (nameLen = __strleneq(name)) == 0) {
+		errno = EINVAL;
+		return (-1);
+	}
+
+	/* Initialize environment. */
+	if (envVars == NULL && __build_env() == -1)
+		return (-1);
+
+	/* Deactivate specified variable. */
+	envNdx = envVarsTotal - 1;
+	if (__findenv(name, nameLen, &envNdx, true) != NULL) {
+		envVars[envNdx].active = false;
+		if (envVars[envNdx].putenv)
+			__remove_putenv(envNdx);
+		__rebuild_environ(envActive - 1);
+	}
+
+	return (0);
 }
diff --git a/lib/libc/stdlib/putenv.c b/lib/libc/stdlib/putenv.c
deleted file mode 100644
index a5eea5d0ddfd..000000000000
--- a/lib/libc/stdlib/putenv.c
+++ /dev/null
@@ -1,56 +0,0 @@
-/*-
- * Copyright (c) 1988, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)putenv.c	8.2 (Berkeley) 3/27/94";
-#endif /* LIBC_SCCS and not lint */
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
-
-#include <stdlib.h>
-#include <string.h>
-
-int
-putenv(str)
-	const char *str;
-{
-	char *p, *equal;
-	int rval;
-
-	if ((p = strdup(str)) == NULL)
-		return (-1);
-	if ((equal = index(p, '=')) == NULL) {
-		(void)free(p);
-		return (-1);
-	}
-	*equal = '\0';
-	rval = setenv(p, equal + 1, 1);
-	(void)free(p);
-	return (rval);
-}
diff --git a/lib/libc/stdlib/setenv.c b/lib/libc/stdlib/setenv.c
deleted file mode 100644
index 202c022ebfcf..000000000000
--- a/lib/libc/stdlib/setenv.c
+++ /dev/null
@@ -1,116 +0,0 @@
-/*
- * Copyright (c) 1987, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)setenv.c	8.1 (Berkeley) 6/4/93";
-#endif /* LIBC_SCCS and not lint */
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
-
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-char *__findenv(const char *, int *);
-
-/*
- * setenv --
- *	Set the value of the environmental variable "name" to be
- *	"value".  If rewrite is set, replace any current value.
- */
-int
-setenv(name, value, rewrite)
-	const char *name;
-	const char *value;
-	int rewrite;
-{
-	extern char **environ;
-	static char **alloced;			/* if allocated space before */
-	char *c;
-	int l_value, offset;
-
-	if (*value == '=')			/* no `=' in value */
-		++value;
-	l_value = strlen(value);
-	if ((c = __findenv(name, &offset))) {	/* find if already exists */
-		if (!rewrite)
-			return (0);
-		if (strlen(c) >= l_value) {	/* old larger; copy over */
-			while ( (*c++ = *value++) );
-			return (0);
-		}
-	} else {					/* create new slot */
-		int cnt;
-		char **p;
-
-		for (p = environ, cnt = 0; *p; ++p, ++cnt);
-		if (alloced == environ) {			/* just increase size */
-			p = (char **)realloc((char *)environ,
-			    (size_t)(sizeof(char *) * (cnt + 2)));
-			if (!p)
-				return (-1);
-			alloced = environ = p;
-		}
-		else {				/* get new space */
-						/* copy old entries into it */
-			p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
-			if (!p)
-				return (-1);
-			bcopy(environ, p, cnt * sizeof(char *));
-			alloced = environ = p;
-		}
-		environ[cnt + 1] = NULL;
-		offset = cnt;
-	}
-	for (c = (char *)name; *c && *c != '='; ++c);	/* no `=' in name */
-	if (!(environ[offset] =			/* name + `=' + value */
-	    malloc((size_t)((int)(c - name) + l_value + 2))))
-		return (-1);
-	for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
-	for (*c++ = '='; (*c++ = *value++); );
-	return (0);
-}
-
-/*
- * unsetenv(name) --
- *	Delete environmental variable "name".
- */
-void
-unsetenv(name)
-	const char *name;
-{
-	extern char **environ;
-	char **p;
-	int offset;
-
-	while (__findenv(name, &offset))	/* if set multiple times */
-		for (p = &environ[offset];; ++p)
-			if (!(*p = *(p + 1)))
-				break;
-}
diff --git a/libexec/pppoed/pppoed.c b/libexec/pppoed/pppoed.c
index 8dfebb70ff27..f07dd8c07d5d 100644
--- a/libexec/pppoed/pppoed.c
+++ b/libexec/pppoed/pppoed.c
@@ -258,7 +258,7 @@ Spawn(const char *prog, const char *acname, const char *provider,
   struct ng_mesg *rep = (struct ng_mesg *)msgbuf;
   struct ngpppoe_sts *sts = (struct ngpppoe_sts *)(msgbuf + sizeof *rep);
   struct ngpppoe_init_data *data;
-  char env[sizeof(HISMACADDR)+18], unknown[14], sessionid[5], *path;
+  char env[18], unknown[14], sessionid[5], *path;
   unsigned char *macaddr;
   const char *msg;
   int ret, slen;
@@ -352,11 +352,11 @@ Spawn(const char *prog, const char *acname, const char *provider,
       /* Put the peer's MAC address in the environment */
       if (sz >= sizeof(struct ether_header)) {
         macaddr = ((struct ether_header *)request)->ether_shost;
-        snprintf(env, sizeof(env), "%s=%x:%x:%x:%x:%x:%x", HISMACADDR,
+        snprintf(env, sizeof(env), "%x:%x:%x:%x:%x:%x",
                  macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4],
                  macaddr[5]);
-        if (putenv(env) != 0)
-          syslog(LOG_INFO, "putenv: cannot set %s: %m", env);
+        if (setenv(HISMACADDR, env, 1) != 0)
+          syslog(LOG_INFO, "setenv: cannot set %s: %m", HISMACADDR);
       }
 
       /* And send our request data to the waiting node */
diff --git a/sys/sys/param.h b/sys/sys/param.h
index d77fa0361700..585731795636 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -57,7 +57,7 @@
  *		is created, otherwise 1.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 700049	/* Master, propagated to newvers */
+#define __FreeBSD_version 700050	/* Master, propagated to newvers */
 
 #ifndef LOCORE
 #include <sys/types.h>
diff --git a/tools/regression/environ/Makefile b/tools/regression/environ/Makefile
new file mode 100644
index 000000000000..62720d28abd1
--- /dev/null
+++ b/tools/regression/environ/Makefile
@@ -0,0 +1,14 @@
+#
+# $FreeBSD$
+#
+PROGS=	envctl retention timings
+
+all clean test:
+.for target in ${.TARGET}
+.for prog in ${PROGS}
+	@${MAKE} -f Makefile.${prog} ${target}
+.endfor
+.if make(clean)
+	rm -f *~
+.endif
+.endfor
diff --git a/tools/regression/environ/Makefile.envctl b/tools/regression/environ/Makefile.envctl
new file mode 100644
index 000000000000..6298a20646dd
--- /dev/null
+++ b/tools/regression/environ/Makefile.envctl
@@ -0,0 +1,16 @@
+#
+# $FreeBSD$
+#
+SRCS=	envctl.c
+PROG=	envctl
+
+CFLAGS+=-Wall -I../../../include
+
+CLEANFILES=	${PROG}.core
+
+NO_MAN=	yes
+
+.include <bsd.prog.mk>
+
+test: ${PROG}
+	@sh envtest.t
diff --git a/tools/regression/environ/Makefile.retention b/tools/regression/environ/Makefile.retention
new file mode 100644
index 000000000000..9e0687f484fe
--- /dev/null
+++ b/tools/regression/environ/Makefile.retention
@@ -0,0 +1,16 @@
+#
+# $FreeBSD$
+#
+SRCS=	retention.c
+PROG=	retention
+
+CFLAGS+=-Wall -I../../../include
+
+CLEANFILES=	*~ ${PROG}.core
+
+NO_MAN=	yes
+
+.include <bsd.prog.mk>
+
+test: ${PROG}
+	@./${PROG}
diff --git a/tools/regression/environ/Makefile.timings b/tools/regression/environ/Makefile.timings
new file mode 100644
index 000000000000..88c4f7c7280b
--- /dev/null
+++ b/tools/regression/environ/Makefile.timings
@@ -0,0 +1,16 @@
+#
+# $FreeBSD$
+#
+SRCS=	timings.c
+PROG=	timings
+
+CFLAGS+=-Wall -I../../../include
+
+CLEANFILES=	${PROG}.core
+
+NO_MAN=	yes
+
+.include <bsd.prog.mk>
+
+test: ${PROG}
+	@./timings
diff --git a/tools/regression/environ/envctl.c b/tools/regression/environ/envctl.c
new file mode 100644
index 000000000000..2681741da723
--- /dev/null
+++ b/tools/regression/environ/envctl.c
@@ -0,0 +1,154 @@
+/*-
+ * Copyright (c) 2007 Sean C. Farley <scf@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer,
+ *    without modification, immediately at the beginning of the file.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <errno.h>
+#include <libgen.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+
+extern char **environ;
+
+
+static void
+dump_environ(void)
+{
+	char **environPtr;
+
+	for (environPtr = environ; *environPtr != NULL; *environPtr++)
+		printf("%s\n", *environPtr);
+
+	return;
+}
+
+
+static void
+usage(const char *program)
+{
+	fprintf(stderr, "Usage:  %s [-DGUcht] [-gu name] [-p name=value] "
+	    "[(-S|-s name) value overwrite]\n\n"
+	    "Options:\n"
+	    "  -D\t\t\t\tDump environ\n"
+	    "  -G name\t\t\tgetenv(NULL)\n"
+	    "  -S value overwrite\t\tsetenv(NULL, value, overwrite)\n"
+	    "  -U\t\t\t\tunsetenv(NULL)\n"
+	    "  -c\t\t\t\tClear environ variable\n"
+	    "  -g name\t\t\tgetenv(name)\n"
+	    "  -h\t\t\t\tHelp\n"
+	    "  -p name=value\t\t\tputenv(name=value)\n"
+	    "  -s name value overwrite\tsetenv(name, value, overwrite)\n"
+	    "  -t\t\t\t\tOutput is suitable for testing (no newlines)\n"
+	    "  -u name\t\t\tunsetenv(name)\n",
+	    basename(program));
+
+	return;
+}
+
+
+int
+main(int argc, char **argv)
+{
+	char *cleanEnv[] = { NULL };
+	char arg;
+	const char *eol = "\n";
+	const char *value;
+
+	if (argc == 1) {
+		usage(argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	while ((arg = getopt(argc, argv, "DGS:Ucg:hp:s:tu:")) != -1) {
+		switch (arg) {
+			case 'D':
+				errno = 0;
+				dump_environ();
+				break;
+
+			case 'c':
+				environ = cleanEnv;
+				break;
+
+			case 'G':
+				value = getenv(NULL);
+				printf("%s%s", value == NULL ? "" : value, eol);
+				break;
+
+			case 'g':
+				value = getenv(optarg);
+				printf("%s%s", value == NULL ? "" : value, eol);
+				break;
+
+			case 'p':
+				errno = 0;
+				printf("%d %d%s", putenv(optarg), errno, eol);
+				break;
+
+			case 'S':
+				errno = 0;
+				printf("%d %d%s", setenv(NULL, optarg,
+				    atoi(argv[optind])), errno, eol);
+				optind += 1;
+				break;
+
+			case 's':
+				errno = 0;
+				printf("%d %d%s", setenv(optarg, argv[optind],
+				    atoi(argv[optind + 1])), errno, eol);
+				optind += 2;
+				break;
+
+			case 't':
+				eol = " ";
+				break;
+
+			case 'U':
+				printf("%d %d%s", unsetenv(NULL), errno, eol);
+				break;
+
+			case 'u':
+				printf("%d %d%s", unsetenv(optarg), errno, eol);
+				break;
+
+			case 'h':
+			default:
+				usage(argv[0]);
+				exit(EXIT_FAILURE);
+		}
+	}
+
+	// Output a closing newline in test mode.
+	if (eol[0] == ' ')
+		printf("\n");
+
+	return (EXIT_SUCCESS);
+}
diff --git a/tools/regression/environ/envtest.t b/tools/regression/environ/envtest.t
new file mode 100644
index 000000000000..e3aca952e2da
--- /dev/null
+++ b/tools/regression/environ/envtest.t
@@ -0,0 +1,182 @@
+#!/bin/sh
+#
+# Copyright (c) 2007 Sean C. Farley <scf@FreeBSD.org>
+# All rights reserved.
+# 
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer,
+#    without modification, immediately at the beginning of the file.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# $FreeBSD$
+
+
+# Initialization.
+testndx=0
+
+
+# Testing function.
+run_test()
+{
+	lasttest="${@}"
+	result=`./envctl -t "${@}"`
+
+	if [ ${?} -ne 0 ]
+	then
+		echo "Test program failed" >&2
+		exit 1
+	fi
+
+	return
+}
+
+
+# Perform test on results.
+check_result()
+{
+	testndx=$((testndx + 1))
+
+	echo "${result}" | sed 's/[ \t]*$//' | grep -q "^${@}$"
+	if [ ${?} -eq 0 ]
+	then
+		echo "ok ${testndx}"
+	else
+		echo "not ok ${testndx} - '${lasttest}'"
+	fi
+
+	return
+}
+
+
+#
+# Regression tests
+#
+
+# Setup environment for tests.
+readonly BAR="bar"
+readonly NEWBAR="newbar"
+export FOO=${BAR}
+
+
+# Gets from environ.
+run_test -g FOO
+check_result "${FOO}"
+
+run_test -c -g FOO
+check_result ""
+
+run_test -g FOOBAR
+check_result ""
+
+run_test -c -g FOOBAR
+check_result ""
+
+run_test -G
+check_result ""
+
+
+# Sets.
+run_test -s FOO ${NEWBAR} 0 -g FOO
+check_result "0 0 ${BAR}"
+
+run_test -s FOO ${NEWBAR} 1 -g FOO
+check_result "0 0 ${NEWBAR}"
+
+run_test -c -s FOO ${NEWBAR} 0 -g FOO
+check_result "0 0 ${NEWBAR}"
+
+run_test -c -s FOO ${NEWBAR} 1 -g FOO
+check_result "0 0 ${NEWBAR}"
+
+run_test -s "FOO=" ${NEWBAR} 1 -g FOO
+check_result "-1 22 ${BAR}"
+
+run_test -s "=FOO" ${NEWBAR} 1
+check_result "-1 22"
+
+run_test -s "=" ${NEWBAR} 1
+check_result "-1 22"
+
+run_test -s "" ${NEWBAR} 1
+check_result "-1 22"
+
+run_test -S ${NEWBAR} 1
+check_result "-1 22"
+
+run_test -s FOO ${NEWBAR} 1 -s FOO ${BAR} 1 -g FOO
+check_result "0 0 0 0 ${BAR}"
+
+run_test -c -s FOO ${NEWBAR} 1 -s FOO ${BAR} 1 -g FOO
+check_result "0 0 0 0 ${BAR}"
+
+run_test -s FOO ${NEWBAR} 1 -s FOO ${BAR} 1 -s FOO ${NEWBAR} 1 -g FOO
+check_result "0 0 0 0 0 0 ${NEWBAR}"
+
+run_test -s FOO ${NEWBAR} 1 -s FOO ${BAR} 1 -s FOO ${NEWBAR} 1 -s FOO ${BAR} 1\
+	-g FOO
+check_result "0 0 0 0 0 0 0 0 ${BAR}"
+
+
+# Unsets.
+run_test -u FOO -g FOO
+check_result "0 0"
+
+run_test -c -u FOO -g FOO
+check_result "0 0"
+
+run_test -U
+check_result "-1 22"
+
+run_test -u ""
+check_result "-1 22"
+
+run_test -u "=${BAR}"
+check_result "-1 22"
+
+run_test -c -s FOO ${NEWBAR} 1 -g FOO -u FOO -g FOO
+check_result "0 0 ${NEWBAR} 0 0"
+
+
+# Puts.
+run_test -p FOO=${NEWBAR} -g FOO
+check_result "0 0 ${NEWBAR}"
+
+run_test -c -p FOO=${NEWBAR} -g FOO
+check_result "0 0 ${NEWBAR}"
+
+run_test -p FOO -g FOO
+check_result "-1 22 ${BAR}"
+
+run_test -p FOO=${BAR} -p FOO=${NEWBAR} -g FOO
+check_result "0 0 0 0 ${NEWBAR}"
+
+run_test -p FOO=${BAR} -s FOO ${NEWBAR} 1 -g FOO
+check_result "0 0 0 0 ${NEWBAR}"
+
+run_test -s FOO ${NEWBAR} 1 -p FOO=${BAR} -g FOO
+check_result "0 0 0 0 ${BAR}"
+
+run_test -p FOO=${BAR} -u FOO
+check_result "0 0 0 0"
+
+run_test -p FOO=${BAR} -s FOO ${NEWBAR} 1 -u FOO
+check_result "0 0 0 0 0 0"
+
+run_test -s FOO ${NEWBAR} 1 -p FOO=${BAR} -u FOO
+check_result "0 0 0 0 0 0"
diff --git a/tools/regression/environ/retention.c b/tools/regression/environ/retention.c
new file mode 100644
index 000000000000..7f75cd100e15
--- /dev/null
+++ b/tools/regression/environ/retention.c
@@ -0,0 +1,109 @@
+/*-
+ * Copyright (c) 2007 Sean C. Farley <scf@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer,
+ *    without modification, immediately at the beginning of the file.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+
+extern char **environ;
+const char *envName = "FOOBAR";
+const char *envValSmall = "Hi";
+const char *envValLarge = "Hi, again";
+const char *envValAny = "Any value";
+
+
+int
+main(int argc, char **argv)
+{
+	const char *env1 = NULL;
+	const char *env2 = NULL;
+	const char *env3 = NULL;
+	const char *env4 = NULL;
+	const char *env5 = NULL;
+	int testNdx;
+
+	/* Clean slate. */
+	environ = NULL;
+	testNdx = 0;
+
+	/* Initial value of variable. */
+	if (getenv(envName) != NULL)
+		printf("not ");
+	printf("ok %d - getenv(\"%s\")\n", ++testNdx, envName);
+
+	/* Set value of variable to smaller value and get value. */
+	if ((setenv(envName, envValSmall, 1) != 0) ||
+	    ((env1 = getenv(envName)) == NULL) ||
+	    (strcmp(env1, envValSmall) != 0))
+		printf("not ");
+	printf("ok %d - setenv(\"%s\", \"%s\", 1)\n", ++testNdx, envName,
+	    envValSmall);
+
+	/* Unset variable. */
+	if ((unsetenv(envName) == -1) || ((env2 = getenv(envName)) != NULL))
+		printf("not ");
+	printf("ok %d - unsetenv(\"%s\")\n", ++testNdx, envName);
+
+	/* Set variable to bigger value and get value. */
+	if ((setenv(envName, envValLarge, 1) != 0) ||
+	    ((env3 = getenv(envName)) == NULL) ||
+	    (strcmp(env3, envValLarge) != 0))
+		printf("not ");
+	printf("ok %d - setenv(\"%s\", \"%s\", 1)\n", ++testNdx, envName,
+	    envValLarge);
+
+	/* Set variable to smaller value and get value. */
+	if ((setenv(envName, envValSmall, 1) != 0) ||
+	    ((env4 = getenv(envName)) == NULL) ||
+	    (strcmp(env4, envValSmall) != 0))
+		printf("not ");
+	printf("ok %d - setenv(\"%s\", \"%s\", 1)\n", ++testNdx, envName,
+	    envValSmall);
+
+	/* Set variable to any value without overwrite and get value. */
+	if ((setenv(envName, envValAny, 0) != 0) ||
+	    ((env5 = getenv(envName)) == NULL) ||
+	    (strcmp(env5, envValAny) == 0))
+		printf("not ");
+	printf("ok %d - setenv(\"%s\", \"%s\", 0)\n", ++testNdx, envName,
+	    envValAny);
+
+	/*
+	 * Verify FreeBSD-ism about allowing a program to keep old pointers without
+	 * risk of segfaulting.
+	 */
+	if ((strcmp(env1, envValSmall) != 0) ||
+	    (strcmp(env3, envValSmall) != 0) ||
+	    (strcmp(env4, envValSmall) != 0))
+		printf("not ");
+	printf("ok %d - old variables point to valid memory\n", ++testNdx);
+
+	exit(EXIT_SUCCESS);
+}
diff --git a/tools/regression/environ/timings.c b/tools/regression/environ/timings.c
new file mode 100644
index 000000000000..1bf3c910a108
--- /dev/null
+++ b/tools/regression/environ/timings.c
@@ -0,0 +1,195 @@
+/*-
+ * Copyright (c) 2007 Sean C. Farley <scf@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include <sys/time.h>
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+
+const char value1[] = "Large ------------------ value";
+const char value2[] = "Small -- value";
+char nameValuePair[] = "less=more";
+const char name[] = "PATH";
+const char name2[] = "SHELL";
+const int MaxIterations = 1000000;
+const char Tabs[] = "\t\t\t";
+
+
+static int
+report_time(const char *action, struct timeval *startTime,
+    struct timeval *endTime)
+{
+	int actionLen;
+	int numTabs;
+
+	actionLen = strlen(action);
+	numTabs = 3 - actionLen / 8;
+
+	return (printf("Time spent executing %s:%.*s%f\n", action, numTabs, Tabs,
+	    (endTime->tv_sec - startTime->tv_sec) +
+	    (double)(endTime->tv_usec - startTime->tv_usec) / 1000000));
+}
+
+
+int
+main(int argc, char **argv)
+{
+	int iterations;
+	struct timeval endTime;
+	struct timeval startTime;
+
+	/*
+	 * getenv() on the existing environment.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		if (getenv(name) == NULL)
+			err(EXIT_FAILURE, "getenv(name)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("getenv(name)", &startTime, &endTime);
+
+
+	/*
+	 * setenv() a variable with a large value.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		if (setenv(name, value1, 1) == -1)
+			err(EXIT_FAILURE, "setenv(name, value1, 1)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("setenv(name, value1, 1)", &startTime, &endTime);
+
+
+	/*
+	 * getenv() the new variable on the new environment.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		/* Set large value to variable. */
+		if (getenv(name) == NULL)
+			err(EXIT_FAILURE, "getenv(name)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("getenv(name)", &startTime, &endTime);
+
+
+	/*
+	 * getenv() a different variable on the new environment.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		/* Set large value to variable. */
+		if (getenv(name2) == NULL)
+			err(EXIT_FAILURE, "getenv(name2)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("getenv(name2)", &startTime, &endTime);
+
+
+	/*
+	 * setenv() a variable with a small value.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		if (setenv(name, value2, 1) == -1)
+			err(EXIT_FAILURE, "setenv(name, value2, 1)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("setenv(name, value2, 1)", &startTime, &endTime);
+
+
+	/*
+	 * getenv() a different variable on the new environment.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		/* Set large value to variable. */
+		if (getenv(name2) == NULL)
+			err(EXIT_FAILURE, "getenv(name)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("getenv(name)", &startTime, &endTime);
+
+
+	/*
+	 * getenv() a different variable on the new environment.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		/* Set large value to variable. */
+		if (getenv(name2) == NULL)
+			err(EXIT_FAILURE, "getenv(name2)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("getenv(name2)", &startTime, &endTime);
+
+
+	/*
+	 * putenv() a variable with a small value.
+	 */
+	gettimeofday(&startTime, NULL);
+
+	/* Iterate over setting variable. */
+	for (iterations = 0; iterations < MaxIterations; iterations++)
+		if (putenv(nameValuePair) == -1)
+			err(EXIT_FAILURE, "putenv(nameValuePair)");
+
+	gettimeofday(&endTime, NULL);
+
+	report_time("putenv(nameValuePair)", &startTime, &endTime);
+
+
+	exit(EXIT_SUCCESS);
+}
diff --git a/usr.bin/du/du.c b/usr.bin/du/du.c
index 00c1f5e728d0..73583e320b94 100644
--- a/usr.bin/du/du.c
+++ b/usr.bin/du/du.c
@@ -140,16 +140,16 @@ main(int argc, char *argv[])
 				cflag = 1;
 				break;
 			case 'h':
-				putenv("BLOCKSIZE=512");
+				setenv("BLOCKSIZE", "512", 1);
 				hflag = 1;
 				break;
 			case 'k':
 				hflag = 0;
-				putenv("BLOCKSIZE=1024");
+				setenv("BLOCKSIZE", "1024", 1);
 				break;
 			case 'm':
 				hflag = 0;
-				putenv("BLOCKSIZE=1048576");
+				setenv("BLOCKSIZE", "1048576", 1);
 				break;
 			case 'n':
 				nodumpflag = 1;
diff --git a/usr.bin/env/env.c b/usr.bin/env/env.c
index 815976fe5f7a..b11a0b772e91 100644
--- a/usr.bin/env/env.c
+++ b/usr.bin/env/env.c
@@ -67,6 +67,7 @@ main(int argc, char **argv)
 	char *altpath, **ep, *p, **parg;
 	char *cleanenv[1];
 	int ch, want_clear;
+	int rtrn;
 
 	altpath = NULL;
 	want_clear = 0;
@@ -105,7 +106,11 @@ main(int argc, char **argv)
 	for (argv += optind; *argv && (p = strchr(*argv, '=')); ++argv) {
 		if (env_verbosity)
 			fprintf(stderr, "#env setenv:\t%s\n", *argv);
-		(void)setenv(*argv, ++p, 1);
+		*p = '\0';
+		rtrn = setenv(*argv, p + 1, 1);
+		*p = '=';
+		if (rtrn == -1)
+			err(EXIT_FAILURE, "setenv %s", *argv);
 	}
 	if (*argv) {
 		if (altpath)
diff --git a/usr.bin/limits/limits.c b/usr.bin/limits/limits.c
index e976f369e2ca..0383ac2a1199 100644
--- a/usr.bin/limits/limits.c
+++ b/usr.bin/limits/limits.c
@@ -244,6 +244,7 @@ main(int argc, char *argv[])
     int rcswhich, shelltype;
     int i, num_limits = 0;
     int ch, doeval = 0, doall = 0;
+    int rtrn;
     login_cap_t * lc = NULL;
     enum { ANY=0, SOFT=1, HARD=2, BOTH=3, DISPLAYONLY=4 } type = ANY;
     enum { RCSUNKNOWN=0, RCSSET=1, RCSSEL=2 } todo = RCSUNKNOWN;
@@ -399,8 +400,13 @@ main(int argc, char *argv[])
 	login_close(lc);
 
 	/* set leading environment variables, like eval(1) */
-	while (*argv && (p = strchr(*argv, '=')))
-	    (void)setenv(*argv++, ++p, 1);
+	while (*argv && (p = strchr(*argv, '='))) {
+		*p = '\0';
+		rtrn = setenv(*argv++, p + 1, 1);
+		*p = '=';
+		if (rtrn == -1)
+			err(EXIT_FAILURE, "setenv %s", *argv);
+	}
 
 	/* Set limits */
 	for (rcswhich = 0; rcswhich < RLIM_NLIMITS; rcswhich++) {
diff --git a/usr.bin/login/login.c b/usr.bin/login/login.c
index 7827ea1da7d2..549e015c160a 100644
--- a/usr.bin/login/login.c
+++ b/usr.bin/login/login.c
@@ -766,10 +766,11 @@ export(const char *s)
 		"SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH",
 		"IFS", "PATH", NULL
 	};
+	char *p;
 	const char **pp;
 	size_t n;
 
-	if (strlen(s) > 1024 || strchr(s, '=') == NULL)
+	if (strlen(s) > 1024 || (p = strchr(s, '=')) == NULL)
 		return (0);
 	if (strncmp(s, "LD_", 3) == 0)
 		return (0);
@@ -778,7 +779,9 @@ export(const char *s)
 		if (s[n] == '=' && strncmp(s, *pp, n) == 0)
 			return (0);
 	}
-	(void)putenv(s);
+	*p = '\0';
+	(void)setenv(s, p + 1, 1);
+	*p = '=';
 	return (1);
 }
 
diff --git a/usr.bin/su/su.c b/usr.bin/su/su.c
index 76f76b61e64d..8bc54720c2a6 100644
--- a/usr.bin/su/su.c
+++ b/usr.bin/su/su.c
@@ -564,10 +564,14 @@ static void
 export_pam_environment(void)
 {
 	char	**pp;
+	char	*p;
 
 	for (pp = environ_pam; *pp != NULL; pp++) {
-		if (ok_to_export(*pp))
-			putenv(*pp);
+		if (ok_to_export(*pp)) {
+			p = strchr(*pp, '=');
+			*p = '\0';
+			setenv(*pp, p + 1, 1);
+		}
 		free(*pp);
 	}
 }
diff --git a/usr.sbin/pstat/pstat.c b/usr.sbin/pstat/pstat.c
index 95f782c4e0cd..15163652921c 100644
--- a/usr.sbin/pstat/pstat.c
+++ b/usr.sbin/pstat/pstat.c
@@ -135,16 +135,16 @@ main(int argc, char *argv[])
 			fileflag = 1;
 			break;
 		case 'g':
-			putenv("BLOCKSIZE=1G");
+			setenv("BLOCKSIZE", "1G", 1);
 			break;
 		case 'h':
 			humanflag = 1;
 			break;
 		case 'k':
-			putenv("BLOCKSIZE=1K");
+			setenv("BLOCKSIZE", "1K", 1);
 			break;
 		case 'm':
-			putenv("BLOCKSIZE=1M");
+			setenv("BLOCKSIZE", "1M", 1);
 			break;
 		case 'M':
 			memf = optarg;
diff --git a/usr.sbin/sade/main.c b/usr.sbin/sade/main.c
index 45ed1bbe4f9a..5496e136c1bb 100644
--- a/usr.sbin/sade/main.c
+++ b/usr.sbin/sade/main.c
@@ -56,7 +56,7 @@ main(int argc, char **argv)
 	/* XXX */
 	char *p = getenv("TERM");
 	if (p && strcmp(p, "cons25") == 0)
-	    putenv("TERM=cons25w");
+	    setenv("TERM", "cons25w", 1);
     }
 #endif
 
diff --git a/usr.sbin/sade/variable.c b/usr.sbin/sade/variable.c
index bbbc2d29d826..7809deb003fa 100644
--- a/usr.sbin/sade/variable.c
+++ b/usr.sbin/sade/variable.c
@@ -296,6 +296,7 @@ free_variables(void)
 void
 pvariable_set(char *var)
 {
+    char *p;
     char tmp[1024];
 
     if (!var)
@@ -307,7 +308,9 @@ pvariable_set(char *var)
     if (index(var, '=') == NULL)
 	msgFatal("Invalid variable format: %s", var);
     strlcat(tmp, var, 1024); 
-    putenv(tmp);
+    p = strchr(tmp, '=');
+    *p = '\0';
+    setenv(tmp, p + 1, 1);
 }
 
 char *
diff --git a/usr.sbin/sysinstall/main.c b/usr.sbin/sysinstall/main.c
index 7af8d44b61d5..149a0dc4256e 100644
--- a/usr.sbin/sysinstall/main.c
+++ b/usr.sbin/sysinstall/main.c
@@ -74,7 +74,7 @@ main(int argc, char **argv)
 	/* XXX */
 	char *p = getenv("TERM");
 	if (p && strcmp(p, "cons25") == 0)
-	    putenv("TERM=cons25w");
+	    setenv("TERM", "cons25w", 1);
     }
 #endif
 
diff --git a/usr.sbin/sysinstall/variable.c b/usr.sbin/sysinstall/variable.c
index e86104fd100a..694b8be44fa2 100644
--- a/usr.sbin/sysinstall/variable.c
+++ b/usr.sbin/sysinstall/variable.c
@@ -301,6 +301,7 @@ free_variables(void)
 void
 pvariable_set(char *var)
 {
+    char *p;
     char tmp[1024];
 
     if (!var)
@@ -312,7 +313,9 @@ pvariable_set(char *var)
     if (index(var, '=') == NULL)
 	msgFatal("Invalid variable format: %s", var);
     strlcat(tmp, var, 1024); 
-    putenv(tmp);
+    p = strchr(tmp, '=');
+    *p = '\0';
+    setenv(tmp, p + 1, 1);
 }
 
 char *