diff --git a/lib/libfetch/common.c b/lib/libfetch/common.c
index 459154f3af1d..34981e94ac3a 100644
--- a/lib/libfetch/common.c
+++ b/lib/libfetch/common.c
@@ -60,7 +60,7 @@ static struct fetcherr _netdb_errlist[] = {
 };
 
 /* End-of-Line */
-static char ENDL[2] = "\r\n";
+static const char ENDL[2] = "\r\n";
 
 
 /*** Error-reporting functions ***********************************************/
@@ -154,7 +154,7 @@ _fetch_syserr(void)
  * Emit status message
  */
 void
-_fetch_info(char *fmt, ...)
+_fetch_info(const char *fmt, ...)
 {
     va_list ap;
     
@@ -171,7 +171,7 @@ _fetch_info(char *fmt, ...)
  * Return the default port for a scheme
  */
 int
-_fetch_default_port(char *scheme)
+_fetch_default_port(const char *scheme)
 {
     struct servent *se;
 
@@ -188,7 +188,7 @@ _fetch_default_port(char *scheme)
  * Return the default proxy port for a scheme
  */
 int
-_fetch_default_proxy_port(char *scheme)
+_fetch_default_proxy_port(const char *scheme)
 {
     if (strcasecmp(scheme, SCHEME_FTP) == 0)
 	return FTP_DEFAULT_PROXY_PORT;
@@ -201,7 +201,7 @@ _fetch_default_proxy_port(char *scheme)
  * Establish a TCP connection to the specified port on the specified host.
  */
 int
-_fetch_connect(char *host, int port, int af, int verbose)
+_fetch_connect(const char *host, int port, int af, int verbose)
 {
     char pbuf[10];
     struct addrinfo hints, *res, *res0;
@@ -333,15 +333,15 @@ _fetch_getln(int fd, char **buf, size_t *size, size_t *len)
  * XXX currently does not enforce timeout
  */
 int
-_fetch_putln(int fd, char *str, size_t len)
+_fetch_putln(int fd, const char *str, size_t len)
 {
     struct iovec iov[2];
     ssize_t wlen;
 
     /* XXX should enforce timeout */
-    iov[0].iov_base = str;
+    iov[0].iov_base = (char *)str;
     iov[0].iov_len = len;
-    iov[1].iov_base = ENDL;
+    iov[1].iov_base = (char *)ENDL;
     iov[1].iov_len = sizeof ENDL;
     wlen = writev(fd, iov, 2);
     DEBUG(fprintf(stderr, "\033[1m>>> %s\n\033[m", str));
@@ -353,7 +353,7 @@ _fetch_putln(int fd, char *str, size_t len)
 
 int
 _fetch_add_entry(struct url_ent **p, int *size, int *len,
-		 char *name, struct url_stat *stat)
+		 const char *name, struct url_stat *stat)
 {
     struct url_ent *tmp;
 
diff --git a/lib/libfetch/common.h b/lib/libfetch/common.h
index 13723a3f83c2..0c67b28e8cec 100644
--- a/lib/libfetch/common.h
+++ b/lib/libfetch/common.h
@@ -44,14 +44,14 @@ struct fetcherr {
 
 void		 _fetch_seterr(struct fetcherr *p, int e);
 void		 _fetch_syserr(void);
-void		 _fetch_info(char *fmt, ...);
-int		 _fetch_default_port(char *);
-int		 _fetch_default_proxy_port(char *);
-int		 _fetch_connect(char *host, int port, int af, int verbose);
+void		 _fetch_info(const char *fmt, ...);
+int		 _fetch_default_port(const char *);
+int		 _fetch_default_proxy_port(const char *);
+int		 _fetch_connect(const char *host, int port, int af, int verbose);
 int		 _fetch_getln(int fd, char **buf, size_t *size, size_t *len);
-int		 _fetch_putln(int fd, char *str, size_t len);
+int		 _fetch_putln(int fd, const char *str, size_t len);
 int		 _fetch_add_entry(struct url_ent **p, int *size, int *len,
-				  char *name, struct url_stat *stat);
+				  const char *name, struct url_stat *stat);
 
 #define _ftp_seterr(n)	 _fetch_seterr(_ftp_errlist, n)
 #define _http_seterr(n)	 _fetch_seterr(_http_errlist, n)
@@ -72,8 +72,9 @@ int		 _fetch_add_entry(struct url_ent **p, int *size, int *len,
  * Note that _http_request() frees purl, which is way ugly but saves us a
  * whole lot of trouble.
  */
-FILE		*_http_request(struct url *URL, char *op, struct url_stat *us,
-			       struct url *purl, char *flags);
+FILE		*_http_request(struct url *URL, const char *op,
+				struct url_stat *us, struct url *purl,
+				const char *flags);
 
 /*
  * Check whether a particular flag is set
diff --git a/lib/libfetch/fetch.3 b/lib/libfetch/fetch.3
index d1918fa2cf0d..702c6bc1c9f7 100644
--- a/lib/libfetch/fetch.3
+++ b/lib/libfetch/fetch.3
@@ -64,61 +64,61 @@
 .Fd #include <stdio.h>
 .Fd #include <fetch.h>
 .Ft struct url *
-.Fn fetchMakeURL "char *scheme" "char *host" "int port" "char *doc" "char *user" "char *pwd"
+.Fn fetchMakeURL "const char *scheme" "const char *host" "int port" "const char *doc" "const char *user" "const char *pwd"
 .Ft struct url *
-.Fn fetchParseURL "char *URL"
+.Fn fetchParseURL "const char *URL"
 .Ft void
-.Fn fetchFreeURL "struct url *URL"
+.Fn fetchFreeURL "struct url *u"
 .Ft FILE *
-.Fn fetchXGetURL "char *URL" "struct url_stat *us" "char *flags"
+.Fn fetchXGetURL "const char *URL" "struct url_stat *us" "const char *flags"
 .Ft FILE *
-.Fn fetchGetURL "char *URL" "char *flags"
+.Fn fetchGetURL "const char *URL" "const char *flags"
 .Ft FILE *
-.Fn fetchPutURL "char *URL" "char *flags"
+.Fn fetchPutURL "const char *URL" "const char *flags"
 .Ft int
-.Fn fetchStatURL "char *URL" "struct url_stat *us" "char *flags"
+.Fn fetchStatURL "const char *URL" "struct url_stat *us" "const char *flags"
 .Ft struct url_ent *
-.Fn fetchListURL "char *URL" "char *flags"
+.Fn fetchListURL "const char *URL" "const char *flags"
 .Ft FILE *
-.Fn fetchXGet "struct url *URL" "struct url_stat *us" "char *flags"
+.Fn fetchXGet "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft FILE *
-.Fn fetchGet "struct url *URL" "char *flags"
+.Fn fetchGet "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchPut "struct url *URL" "char *flags"
+.Fn fetchPut "struct url *u" "const char *flags"
 .Ft int
-.Fn fetchStat "struct url *URL" "struct url_stat *us" "char *flags"
+.Fn fetchStat "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft struct url_ent *
-.Fn fetchList "struct url *" "char *flags"
+.Fn fetchList "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchXGetFile "struct url *u" "struct url_stat *us" "char *flags"
+.Fn fetchXGetFile "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft FILE *
-.Fn fetchGetFile "struct url *u" "char *flags"
+.Fn fetchGetFile "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchPutFile "struct url *u" "char *flags"
+.Fn fetchPutFile "struct url *u" "const char *flags"
 .Ft int
-.Fn fetchStatFile "struct url *URL" "struct url_stat *us" "char *flags"
+.Fn fetchStatFile "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft struct url_ent *
-.Fn fetchListFile "struct url *" "char *flags"
+.Fn fetchListFile "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchXGetHTTP "struct url *u" "struct url_stat *us" "char *flags"
+.Fn fetchXGetHTTP "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft FILE *
-.Fn fetchGetHTTP "struct url *u" "char *flags"
+.Fn fetchGetHTTP "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchPutHTTP "struct url *u" "char *flags"
+.Fn fetchPutHTTP "struct url *u" "const char *flags"
 .Ft int
-.Fn fetchStatHTTP "struct url *URL" "struct url_stat *us" "char *flags"
+.Fn fetchStatHTTP "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft struct url_ent *
-.Fn fetchListHTTP "struct url *" "char *flags"
+.Fn fetchListHTTP "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchXGetFTP "struct url *u" "struct url_stat *us" "char *flags"
+.Fn fetchXGetFTP "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft FILE *
-.Fn fetchGetFTP "struct url *u" "char *flags"
+.Fn fetchGetFTP "struct url *u" "const char *flags"
 .Ft FILE *
-.Fn fetchPutFTP "struct url *u" "char *flags"
+.Fn fetchPutFTP "struct url *u" "const char *flags"
 .Ft int
-.Fn fetchStatFTP "struct url *URL" "struct url_stat *us" "char *flags"
+.Fn fetchStatFTP "struct url *u" "struct url_stat *us" "const char *flags"
 .Ft struct url_ent *
-.Fn fetchListFTP "struct url *" "char *flags"
+.Fn fetchListFTP "struct url *u" "const char *flags"
 .Sh DESCRIPTION
 .Pp
 These functions implement a high-level library for retrieving and
diff --git a/lib/libfetch/fetch.c b/lib/libfetch/fetch.c
index bc803d5f8417..de23f0045246 100644
--- a/lib/libfetch/fetch.c
+++ b/lib/libfetch/fetch.c
@@ -70,7 +70,7 @@ static struct fetcherr _url_errlist[] = {
  * Also fill out the struct url_stat.
  */
 FILE *
-fetchXGet(struct url *URL, struct url_stat *us, char *flags)
+fetchXGet(struct url *URL, struct url_stat *us, const char *flags)
 {
     int direct;
 
@@ -92,7 +92,7 @@ fetchXGet(struct url *URL, struct url_stat *us, char *flags)
  * read-only stream connected to the document referenced by the URL.
  */
 FILE *
-fetchGet(struct url *URL, char *flags)
+fetchGet(struct url *URL, const char *flags)
 {
     return fetchXGet(URL, NULL, flags);
 }
@@ -102,7 +102,7 @@ fetchGet(struct url *URL, char *flags)
  * write-only stream connected to the document referenced by the URL.
  */
 FILE *
-fetchPut(struct url *URL, char *flags)
+fetchPut(struct url *URL, const char *flags)
 {
     int direct;
 
@@ -124,7 +124,7 @@ fetchPut(struct url *URL, char *flags)
  * size of the document referenced by the URL if it exists.
  */
 int
-fetchStat(struct url *URL, struct url_stat *us, char *flags)
+fetchStat(struct url *URL, struct url_stat *us, const char *flags)
 {
     int direct;
 
@@ -146,7 +146,7 @@ fetchStat(struct url *URL, struct url_stat *us, char *flags)
  * list of files in the directory pointed to by the URL.
  */
 struct url_ent *
-fetchList(struct url *URL, char *flags)
+fetchList(struct url *URL, const char *flags)
 {
     int direct;
 
@@ -167,7 +167,7 @@ fetchList(struct url *URL, char *flags)
  * Attempt to parse the given URL; if successful, call fetchXGet().
  */
 FILE *
-fetchXGetURL(char *URL, struct url_stat *us, char *flags)
+fetchXGetURL(const char *URL, struct url_stat *us, const char *flags)
 {
     struct url *u;
     FILE *f;
@@ -185,7 +185,7 @@ fetchXGetURL(char *URL, struct url_stat *us, char *flags)
  * Attempt to parse the given URL; if successful, call fetchGet().
  */
 FILE *
-fetchGetURL(char *URL, char *flags)
+fetchGetURL(const char *URL, const char *flags)
 {
     return fetchXGetURL(URL, NULL, flags);
 }
@@ -194,7 +194,7 @@ fetchGetURL(char *URL, char *flags)
  * Attempt to parse the given URL; if successful, call fetchPut().
  */
 FILE *
-fetchPutURL(char *URL, char *flags)
+fetchPutURL(const char *URL, const char *flags)
 {
     struct url *u;
     FILE *f;
@@ -212,7 +212,7 @@ fetchPutURL(char *URL, char *flags)
  * Attempt to parse the given URL; if successful, call fetchStat().
  */
 int
-fetchStatURL(char *URL, struct url_stat *us, char *flags)
+fetchStatURL(const char *URL, struct url_stat *us, const char *flags)
 {
     struct url *u;
     int s;
@@ -230,7 +230,7 @@ fetchStatURL(char *URL, struct url_stat *us, char *flags)
  * Attempt to parse the given URL; if successful, call fetchList().
  */
 struct url_ent *
-fetchListURL(char *URL, char *flags)
+fetchListURL(const char *URL, const char *flags)
 {
     struct url *u;
     struct url_ent *ue;
@@ -248,8 +248,8 @@ fetchListURL(char *URL, char *flags)
  * Make a URL
  */
 struct url *
-fetchMakeURL(char *scheme, char *host, int port, char *doc,
-    char *user, char *pwd)
+fetchMakeURL(const char *scheme, const char *host, int port, const char *doc,
+    const char *user, const char *pwd)
 {
     struct url *u;
 
@@ -292,9 +292,10 @@ fetchMakeURL(char *scheme, char *host, int port, char *doc,
  * This almost, but not quite, RFC1738 URL syntax.
  */
 struct url *
-fetchParseURL(char *URL)
+fetchParseURL(const char *URL)
 {
-    char *doc, *p, *q;
+    char *doc;
+    const char *p, *q;
     struct url *u;
     int i;
 
diff --git a/lib/libfetch/fetch.h b/lib/libfetch/fetch.h
index bc944c8b9931..dc5fc05b4702 100644
--- a/lib/libfetch/fetch.h
+++ b/lib/libfetch/fetch.h
@@ -87,41 +87,42 @@ struct url_ent {
 #define	FETCH_VERBOSE	19
 
 /* FILE-specific functions */
-FILE		*fetchXGetFile(struct url *, struct url_stat *, char *);
-FILE		*fetchGetFile(struct url *, char *);
-FILE		*fetchPutFile(struct url *, char *);
-int		 fetchStatFile(struct url *, struct url_stat *, char *);
-struct url_ent	*fetchListFile(struct url *, char *);
+FILE		*fetchXGetFile(struct url *, struct url_stat *, const char *);
+FILE		*fetchGetFile(struct url *, const char *);
+FILE		*fetchPutFile(struct url *, const char *);
+int		 fetchStatFile(struct url *, struct url_stat *, const char *);
+struct url_ent	*fetchListFile(struct url *, const char *);
 
 /* HTTP-specific functions */
-FILE		*fetchXGetHTTP(struct url *, struct url_stat *, char *);
-FILE		*fetchGetHTTP(struct url *, char *);
-FILE		*fetchPutHTTP(struct url *, char *);
-int		 fetchStatHTTP(struct url *, struct url_stat *, char *);
-struct url_ent	*fetchListHTTP(struct url *, char *);
+FILE		*fetchXGetHTTP(struct url *, struct url_stat *, const char *);
+FILE		*fetchGetHTTP(struct url *, const char *);
+FILE		*fetchPutHTTP(struct url *, const char *);
+int		 fetchStatHTTP(struct url *, struct url_stat *, const char *);
+struct url_ent	*fetchListHTTP(struct url *, const char *);
 
 /* FTP-specific functions */
-FILE		*fetchXGetFTP(struct url *, struct url_stat *, char *);
-FILE		*fetchGetFTP(struct url *, char *);
-FILE		*fetchPutFTP(struct url *, char *);
-int		 fetchStatFTP(struct url *, struct url_stat *, char *);
-struct url_ent	*fetchListFTP(struct url *, char *);
+FILE		*fetchXGetFTP(struct url *, struct url_stat *, const char *);
+FILE		*fetchGetFTP(struct url *, const char *);
+FILE		*fetchPutFTP(struct url *, const char *);
+int		 fetchStatFTP(struct url *, struct url_stat *, const char *);
+struct url_ent	*fetchListFTP(struct url *, const char *);
 
 /* Generic functions */
-FILE		*fetchXGetURL(char *, struct url_stat *, char *);
-FILE		*fetchGetURL(char *, char *);
-FILE		*fetchPutURL(char *, char *);
-int		 fetchStatURL(char *, struct url_stat *, char *);
-struct url_ent	*fetchListURL(char *, char *);
-FILE		*fetchXGet(struct url *, struct url_stat *, char *);
-FILE		*fetchGet(struct url *, char *);
-FILE		*fetchPut(struct url *, char *);
-int		 fetchStat(struct url *, struct url_stat *, char *);
-struct url_ent	*fetchList(struct url *, char *);
+FILE		*fetchXGetURL(const char *, struct url_stat *, const char *);
+FILE		*fetchGetURL(const char *, const char *);
+FILE		*fetchPutURL(const char *, const char *);
+int		 fetchStatURL(const char *, struct url_stat *, const char *);
+struct url_ent	*fetchListURL(const char *, const char *);
+FILE		*fetchXGet(struct url *, struct url_stat *, const char *);
+FILE		*fetchGet(struct url *, const char *);
+FILE		*fetchPut(struct url *, const char *);
+int		 fetchStat(struct url *, struct url_stat *, const char *);
+struct url_ent	*fetchList(struct url *, const char *);
 
 /* URL parsing */
-struct url	*fetchMakeURL(char *, char *, int, char *, char *, char *);
-struct url	*fetchParseURL(char *);
+struct url	*fetchMakeURL(const char *, const char *, int,
+			const char *, const char *, const char *);
+struct url	*fetchParseURL(const char *);
 void		 fetchFreeURL(struct url *);
 
 /* Last error code */
diff --git a/lib/libfetch/file.c b/lib/libfetch/file.c
index 5d591432547c..2db091db3f25 100644
--- a/lib/libfetch/file.c
+++ b/lib/libfetch/file.c
@@ -39,7 +39,7 @@
 #include "common.h"
 
 FILE *
-fetchXGetFile(struct url *u, struct url_stat *us, char *flags)
+fetchXGetFile(struct url *u, struct url_stat *us, const char *flags)
 {
     FILE *f;
     
@@ -60,13 +60,13 @@ fetchXGetFile(struct url *u, struct url_stat *us, char *flags)
 }
 
 FILE *
-fetchGetFile(struct url *u, char *flags)
+fetchGetFile(struct url *u, const char *flags)
 {
     return fetchXGetFile(u, NULL, flags);    
 }
 
 FILE *
-fetchPutFile(struct url *u, char *flags)
+fetchPutFile(struct url *u, const char *flags)
 {
     FILE *f;
     
@@ -87,7 +87,7 @@ fetchPutFile(struct url *u, char *flags)
 }
 
 static int
-_fetch_stat_file(char *fn, struct url_stat *us)
+_fetch_stat_file(const char *fn, struct url_stat *us)
 {
     struct stat sb;
 
@@ -104,13 +104,13 @@ _fetch_stat_file(char *fn, struct url_stat *us)
 }
 
 int
-fetchStatFile(struct url *u, struct url_stat *us, char *flags)
+fetchStatFile(struct url *u, struct url_stat *us, const char *flags)
 {
     return _fetch_stat_file(u->doc, us);
 }
 
 struct url_ent *
-fetchListFile(struct url *u, char *flags)
+fetchListFile(struct url *u, const char *flags)
 {
     DIR *dir;
     struct dirent *de;
diff --git a/lib/libfetch/ftp.c b/lib/libfetch/ftp.c
index a2dfc93d1bb2..09b72ca7e4ad 100644
--- a/lib/libfetch/ftp.c
+++ b/lib/libfetch/ftp.c
@@ -60,6 +60,7 @@
 #include <netinet/in.h>
 
 #include <ctype.h>
+#include <err.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <netdb.h>
@@ -166,7 +167,7 @@ _ftp_chkerr(int cd)
  * Send a command and check reply
  */
 static int
-_ftp_cmd(int cd, char *fmt, ...)
+_ftp_cmd(int cd, const char *fmt, ...)
 {
     va_list ap;
     size_t len;
@@ -197,8 +198,8 @@ _ftp_cmd(int cd, char *fmt, ...)
 /*
  * Return a pointer to the filename part of a path
  */
-static char *
-_ftp_filename(char *file)
+static const char *
+_ftp_filename(const char *file)
 {
     char *s;
     
@@ -213,7 +214,7 @@ _ftp_filename(char *file)
  * specified file.
  */
 static int
-_ftp_cwd(int cd, char *file)
+_ftp_cwd(int cd, const char *file)
 {
     char *s;
     int e;
@@ -234,9 +235,10 @@ _ftp_cwd(int cd, char *file)
  * Request and parse file stats
  */
 static int
-_ftp_stat(int cd, char *file, struct url_stat *us)
+_ftp_stat(int cd, const char *file, struct url_stat *us)
 {
-    char *ln, *s;
+    char *ln;
+    const char *s;
     struct tm tm;
     time_t t;
     int e;
@@ -447,8 +449,8 @@ _ftp_setup(int csd, int dsd, int mode)
  * Transfer file
  */
 static FILE *
-_ftp_transfer(int cd, char *oper, char *file,
-	      int mode, off_t offset, char *flags)
+_ftp_transfer(int cd, const char *oper, const char *file,
+	      int mode, off_t offset, const char *flags)
 {
     struct sockaddr_storage sin;
     struct sockaddr_in6 *sin6;
@@ -716,7 +718,7 @@ _ftp_transfer(int cd, char *oper, char *file,
  * Log on to FTP server
  */
 static int
-_ftp_connect(struct url *url, struct url *purl, char *flags)
+_ftp_connect(struct url *url, struct url *purl, const char *flags)
 {
     int cd, e, direct, verbose;
 #ifdef INET6
@@ -725,7 +727,8 @@ _ftp_connect(struct url *url, struct url *purl, char *flags)
     int af = AF_INET;
 #endif
     const char *logname;
-    char *user, *pwd;
+    const char *user;
+    const char *pwd;
     char localhost[MAXHOSTNAMELEN];
     char pbuf[MAXHOSTNAMELEN + MAXLOGNAME + 1];
 
@@ -842,7 +845,7 @@ _ftp_isconnected(struct url *url)
  * Check the cache, reconnect if no luck
  */
 static int
-_ftp_cached_connect(struct url *url, struct url *purl, char *flags)
+_ftp_cached_connect(struct url *url, struct url *purl, const char *flags)
 {
     int e, cd;
 
@@ -901,7 +904,7 @@ _ftp_get_proxy(void)
  * Get and stat file
  */
 FILE *
-fetchXGetFTP(struct url *url, struct url_stat *us, char *flags)
+fetchXGetFTP(struct url *url, struct url_stat *us, const char *flags)
 {
     struct url *purl;
     int cd;
@@ -939,7 +942,7 @@ fetchXGetFTP(struct url *url, struct url_stat *us, char *flags)
  * Get file
  */
 FILE *
-fetchGetFTP(struct url *url, char *flags)
+fetchGetFTP(struct url *url, const char *flags)
 {
     return fetchXGetFTP(url, NULL, flags);
 }
@@ -948,7 +951,7 @@ fetchGetFTP(struct url *url, char *flags)
  * Put file
  */
 FILE *
-fetchPutFTP(struct url *url, char *flags)
+fetchPutFTP(struct url *url, const char *flags)
 {
     struct url *purl;
     int cd;
@@ -982,7 +985,7 @@ fetchPutFTP(struct url *url, char *flags)
  * Get file stats
  */
 int
-fetchStatFTP(struct url *url, struct url_stat *us, char *flags)
+fetchStatFTP(struct url *url, struct url_stat *us, const char *flags)
 {
     struct url *purl;
     int cd;
@@ -1019,9 +1022,8 @@ fetchStatFTP(struct url *url, struct url_stat *us, char *flags)
 /*
  * List a directory
  */
-extern void warnx(char *, ...);
 struct url_ent *
-fetchListFTP(struct url *url, char *flags)
+fetchListFTP(struct url *url, const char *flags)
 {
     warnx("fetchListFTP(): not implemented");
     return NULL;
diff --git a/lib/libfetch/http.c b/lib/libfetch/http.c
index 5c22097987d1..b1332b31588c 100644
--- a/lib/libfetch/http.c
+++ b/lib/libfetch/http.c
@@ -300,7 +300,7 @@ typedef enum {
 /* Names of interesting headers */
 static struct {
     hdr		 num;
-    char	*name;
+    const char	*name;
 } hdr_names[] = {
     { hdr_content_length,	"Content-Length" },
     { hdr_content_range,	"Content-Range" },
@@ -318,7 +318,7 @@ static size_t	 reply_length;
  * Send a formatted line; optionally echo to terminal
  */
 static int
-_http_cmd(int fd, char *fmt, ...)
+_http_cmd(int fd, const char *fmt, ...)
 {
     va_list ap;
     size_t len;
@@ -386,8 +386,8 @@ _http_get_reply(int fd)
  * Check a header; if the type matches the given string, return a
  * pointer to the beginning of the value.
  */
-static char *
-_http_match(char *str, char *hdr)
+static const char *
+_http_match(const char *str, const char *hdr)
 {
     while (*str && *hdr && tolower(*str++) == tolower(*hdr++))
 	/* nothing */;
@@ -402,7 +402,7 @@ _http_match(char *str, char *hdr)
  * Get the next header and return the appropriate symbolic code.
  */
 static hdr
-_http_next_header(int fd, char **p)
+_http_next_header(int fd, const char **p)
 {
     int i;
     
@@ -429,7 +429,7 @@ _http_next_header(int fd, char **p)
  * Parse a last-modified header
  */
 static int
-_http_parse_mtime(char *p, time_t *mtime)
+_http_parse_mtime(const char *p, time_t *mtime)
 {
     char locale[64], *r;
     struct tm tm;
@@ -453,7 +453,7 @@ _http_parse_mtime(char *p, time_t *mtime)
  * Parse a content-length header
  */
 static int
-_http_parse_length(char *p, off_t *length)
+_http_parse_length(const char *p, off_t *length)
 {
     off_t len;
     
@@ -468,7 +468,7 @@ _http_parse_length(char *p, off_t *length)
  * Parse a content-range header
  */
 static int
-_http_parse_range(char *p, off_t *offset, off_t *length, off_t *size)
+_http_parse_range(const char *p, off_t *offset, off_t *length, off_t *size)
 {
     int first, last, len;
 
@@ -559,7 +559,7 @@ _http_base64(char *src)
  * Encode username and password
  */
 static int
-_http_basic_auth(int fd, char *hdr, char *usr, char *pwd)
+_http_basic_auth(int fd, const char *hdr, const char *usr, const char *pwd)
 {
     char *upw, *auth;
     int r;
@@ -579,7 +579,7 @@ _http_basic_auth(int fd, char *hdr, char *usr, char *pwd)
  * Send an authorization header
  */
 static int
-_http_authorize(int fd, char *hdr, char *p)
+_http_authorize(int fd, const char *hdr, const char *p)
 {
     /* basic authorization */
     if (strncasecmp(p, "basic:", 6) == 0) {
@@ -612,7 +612,7 @@ _http_authorize(int fd, char *hdr, char *p)
  * Connect to the correct HTTP server or proxy. 
  */
 static int
-_http_connect(struct url *URL, struct url *purl, char *flags)
+_http_connect(struct url *URL, struct url *purl, const char *flags)
 {
     int verbose;
     int af, fd;
@@ -646,7 +646,7 @@ _http_connect(struct url *URL, struct url *purl, char *flags)
 }
 
 static struct url *
-_http_get_proxy()
+_http_get_proxy(void)
 {
     struct url *purl;
     char *p;
@@ -673,15 +673,15 @@ _http_get_proxy()
  * Send a request and process the reply
  */
 FILE *
-_http_request(struct url *URL, char *op, struct url_stat *us,
-	      struct url *purl, char *flags)
+_http_request(struct url *URL, const char *op, struct url_stat *us,
+	      struct url *purl, const char *flags)
 {
     struct url *url, *new;
     int chunked, direct, need_auth, noredirect, verbose;
     int code, fd, i, n;
     off_t offset, clength, length, size;
     time_t mtime;
-    char *p;
+    const char *p;
     FILE *f;
     hdr h;
     char *host;
@@ -960,7 +960,7 @@ _http_request(struct url *URL, char *op, struct url_stat *us,
  * Retrieve and stat a file by HTTP
  */
 FILE *
-fetchXGetHTTP(struct url *URL, struct url_stat *us, char *flags)
+fetchXGetHTTP(struct url *URL, struct url_stat *us, const char *flags)
 {
     return _http_request(URL, "GET", us, _http_get_proxy(), flags);
 }
@@ -969,7 +969,7 @@ fetchXGetHTTP(struct url *URL, struct url_stat *us, char *flags)
  * Retrieve a file by HTTP
  */
 FILE *
-fetchGetHTTP(struct url *URL, char *flags)
+fetchGetHTTP(struct url *URL, const char *flags)
 {
     return fetchXGetHTTP(URL, NULL, flags);
 }
@@ -978,7 +978,7 @@ fetchGetHTTP(struct url *URL, char *flags)
  * Store a file by HTTP
  */
 FILE *
-fetchPutHTTP(struct url *URL, char *flags)
+fetchPutHTTP(struct url *URL, const char *flags)
 {
     warnx("fetchPutHTTP(): not implemented");
     return NULL;
@@ -988,7 +988,7 @@ fetchPutHTTP(struct url *URL, char *flags)
  * Get an HTTP document's metadata
  */
 int
-fetchStatHTTP(struct url *URL, struct url_stat *us, char *flags)
+fetchStatHTTP(struct url *URL, struct url_stat *us, const char *flags)
 {
     FILE *f;
     
@@ -1002,7 +1002,7 @@ fetchStatHTTP(struct url *URL, struct url_stat *us, char *flags)
  * List a directory
  */
 struct url_ent *
-fetchListHTTP(struct url *url, char *flags)
+fetchListHTTP(struct url *url, const char *flags)
 {
     warnx("fetchListHTTP(): not implemented");
     return NULL;