diff --git a/usr.bin/cksum/Makefile b/usr.bin/cksum/Makefile
index 4c1d027c04b0..1da732b016b6 100644
--- a/usr.bin/cksum/Makefile
+++ b/usr.bin/cksum/Makefile
@@ -1,8 +1,9 @@
 #	@(#)Makefile	8.2 (Berkeley) 4/28/95
+# $FreeBSD$
 
 PROG=	cksum
-CFLAGS+=-Wall
 SRCS=	cksum.c crc.c print.c sum1.c sum2.c crc32.c
+WARNS?=	2
 LINKS=	${BINDIR}/cksum ${BINDIR}/sum
 MLINKS=	cksum.1 sum.1
 
diff --git a/usr.bin/cksum/cksum.c b/usr.bin/cksum/cksum.c
index d89f07fa9ac2..bd75151162d7 100644
--- a/usr.bin/cksum/cksum.c
+++ b/usr.bin/cksum/cksum.c
@@ -66,7 +66,7 @@ main(argc, argv)
 	int argc;
 	char **argv;
 {
-	register int ch, fd, rval;
+	int ch, fd, rval;
 	u_int32_t len, val;
 	char *fn, *p;
 	int (*cfncn) __P((int, u_int32_t *, u_int32_t *));
diff --git a/usr.bin/cksum/crc.c b/usr.bin/cksum/crc.c
index 1dc0293447a9..ba436601c711 100644
--- a/usr.bin/cksum/crc.c
+++ b/usr.bin/cksum/crc.c
@@ -45,6 +45,8 @@ static const char rcsid[] =
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "extern.h"
+
 static const u_int32_t crctab[] = {
 	0x0,
 	0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
@@ -110,21 +112,21 @@ u_int32_t crc_total = ~0;			/* The crc over a number of files. */
 
 int
 crc(fd, cval, clen)
-	register int fd;
+	int fd;
 	u_int32_t *cval, *clen;
 {
-	register u_char *p;
-	register int nr;
-	register u_int32_t crc, len;
+	u_char *p;
+	int nr;
+	u_int32_t lcrc, len;
 	u_char buf[16 * 1024];
 
 #define	COMPUTE(var, ch)	(var) = (var) << 8 ^ crctab[(var) >> 24 ^ (ch)]
 
-	crc = len = 0;
+	lcrc = len = 0;
 	crc_total = ~crc_total;
 	while ((nr = read(fd, buf, sizeof(buf))) > 0)
 		for (len += nr, p = buf; nr--; ++p) {
-			COMPUTE(crc, *p);
+			COMPUTE(lcrc, *p);
 			COMPUTE(crc_total, *p);
 		}
 	if (nr < 0)
@@ -134,11 +136,11 @@ crc(fd, cval, clen)
 
 	/* Include the length of the file. */
 	for (; len != 0; len >>= 8) {
-		COMPUTE(crc, len & 0xff);
+		COMPUTE(lcrc, len & 0xff);
 		COMPUTE(crc_total, len & 0xff);
 	}
 
-	*cval = ~crc;
+	*cval = ~lcrc;
 	crc_total = ~crc_total;
 	return (0);
 }
diff --git a/usr.bin/cksum/crc32.c b/usr.bin/cksum/crc32.c
index ae49a834ecfc..f290d69e6339 100644
--- a/usr.bin/cksum/crc32.c
+++ b/usr.bin/cksum/crc32.c
@@ -18,6 +18,8 @@ static const char rcsid[] =
 
 #include <sys/types.h>
 
+#include "extern.h"
+
 #define CRC(crc, ch)	 (crc = (crc >> 8) ^ crctab[(crc ^ (ch)) & 0xff])
 
 /* generated using the AUTODIN II polynomial
@@ -99,10 +101,10 @@ u_int32_t crc32_total = 0 ;
 
 int
 crc32(fd, cval, clen)
-    register int fd;
+    int fd;
     u_int32_t *cval, *clen;
 {
-    u_int32_t crc = ~0;
+    u_int32_t lcrc = ~0;
     char buf[BUFSIZ], *p ;
     int len, nr ;
 	
@@ -110,14 +112,14 @@ crc32(fd, cval, clen)
     crc32_total = ~crc32_total ;
     while ((nr = read(fd, buf, sizeof(buf))) > 0)
         for (len += nr, p = buf; nr--; ++p) {
-	    CRC(crc, *p) ;
+	    CRC(lcrc, *p) ;
 	    CRC(crc32_total, *p) ;
 	}
     if (nr < 0)
         return 1 ;
 
     *clen = len ;
-    *cval = ~crc ;
+    *cval = ~lcrc ;
     crc32_total = ~crc32_total ;
     return 0 ;
 }
diff --git a/usr.bin/cksum/extern.h b/usr.bin/cksum/extern.h
index cee3f242448c..ab1ee7319b2d 100644
--- a/usr.bin/cksum/extern.h
+++ b/usr.bin/cksum/extern.h
@@ -31,6 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)extern.h	8.1 (Berkeley) 6/6/93
+ * $FreeBSD$
  */
 
 #include <sys/cdefs.h>
diff --git a/usr.bin/cksum/sum1.c b/usr.bin/cksum/sum1.c
index bcdeb30df5a7..aaba1e8cbccd 100644
--- a/usr.bin/cksum/sum1.c
+++ b/usr.bin/cksum/sum1.c
@@ -42,32 +42,34 @@ static const char rcsid[] =
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "extern.h"
+
 int
 csum1(fd, cval, clen)
-	register int fd;
+	int fd;
 	u_int32_t *cval, *clen;
 {
-	register u_int32_t total;
-	register int nr;
-	register u_int crc;
-	register u_char *p;
+	u_int32_t total;
+	int nr;
+	u_int lcrc;
+	u_char *p;
 	u_char buf[8192];
 
 	/*
 	 * 16-bit checksum, rotating right before each addition;
 	 * overflow is discarded.
 	 */
-	crc = total = 0;
+	lcrc = total = 0;
 	while ((nr = read(fd, buf, sizeof(buf))) > 0)
 		for (total += nr, p = buf; nr--; ++p) {
-			if (crc & 1)
-				crc |= 0x10000;
-			crc = ((crc >> 1) + *p) & 0xffff;
+			if (lcrc & 1)
+				lcrc |= 0x10000;
+			lcrc = ((lcrc >> 1) + *p) & 0xffff;
 		}
 	if (nr < 0)
 		return(1);
 
-	*cval = crc;
+	*cval = lcrc;
 	*clen = total;
 	return(0);
 }
diff --git a/usr.bin/cksum/sum2.c b/usr.bin/cksum/sum2.c
index 4ce83f615cfd..a14c4d323ba1 100644
--- a/usr.bin/cksum/sum2.c
+++ b/usr.bin/cksum/sum2.c
@@ -42,14 +42,16 @@ static const char rcsid[] =
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "extern.h"
+
 int
 csum2(fd, cval, clen)
-	register int fd;
+	int fd;
 	u_int32_t *cval, *clen;
 {
-	register u_int32_t crc, total;
-	register int nr;
-	register u_char *p;
+	u_int32_t lcrc, total;
+	int nr;
+	u_char *p;
 	u_char buf[8192];
 
 	/*
@@ -57,19 +59,19 @@ csum2(fd, cval, clen)
 	 *
 	 *   s = sum of all bytes
 	 *   r = s % 2^16 + (s % 2^32) / 2^16
-	 * crc = (r % 2^16) + r / 2^16
+	 * lcrc = (r % 2^16) + r / 2^16
 	 */
-	crc = total = 0;
+	lcrc = total = 0;
 	while ((nr = read(fd, buf, sizeof(buf))) > 0)
 		for (total += nr, p = buf; nr--; ++p)
-			crc += *p;
+			lcrc += *p;
 	if (nr < 0)
 		return(1);
 
-	crc = (crc & 0xffff) + (crc >> 16);
-	crc = (crc & 0xffff) + (crc >> 16);
+	lcrc = (lcrc & 0xffff) + (lcrc >> 16);
+	lcrc = (lcrc & 0xffff) + (lcrc >> 16);
 
-	*cval = crc;
+	*cval = lcrc;
 	*clen = total;
 	return(0);
 }