diff --git a/ChangeLog b/ChangeLog
index 2ec995e..1353858 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -79,6 +79,9 @@
 	  display_string() that have been used in the search prompt
 	  since 1.3.0. (David Benbennick)
 - utils.c:
+  is_blank_char()
+	- Add new function is_blank_char() as an isblank() equivalent,
+	  since isblank() is a GNU extension. (DLR)
   nstricmp(), nstrnicmp()
 	- Add extra blank lines for greater readability, and remove
 	  unneeded test for n's being less than zero (since it's already
@@ -88,6 +91,8 @@
 	- Rename to nstristr() to avoid a potential conflict with an
 	  existing stristr() function, and move up to just after
 	  nstrnicmp(). (DLR)  David Benbennick: Tweak for efficiency.
+	- Include and use only when strcasestr() is unavailable, since
+	  strcasestr() is a GNU extension. (DLR)
 - winio.c:
   get_verbatim_kbinput()
 	- Refactor the output in the DEBUG #ifdef.  It didn't work
@@ -120,6 +125,10 @@
 	- Use napms() instead of nanosleep(), as it does the same thing
 	  (aside from taking an argument in milliseconds instead of
 	  microseconds) and curses includes it. (DLR)
+- configure.ac:
+	- Add tests for isblank() and strcasestr(), and define
+	  _GNU_SOURCE so that the tests work properly.  Increase the
+	  minimum required autoconf version to 2.54. (DLR)
 - faq.html:
 	- Removed question about the NumLock glitch, as it's no longer
 	  needed. (DLR)
@@ -137,6 +146,13 @@
 - nanorc.sample:
 	- Add missing mouse entry, and update the nanorc sample regexes
 	  to account for the backupdir and mouse options. (DLR)
+- README.CVS:
+	- Increase the minimum required autoconf version to 2.54, and
+	  change the recommended automake version 1.7 to the minimum
+	  required automake version.  Note that autoconf 2.54 will
+	  technically also work with automake 1.6c, but that is a CVS
+	  version as opposed to a stable release version, and automake
+	  1.7 requires at least autoconf 2.54 in any case. (DLR)
 
 GNU nano 1.3.2 - 2004.03.31
 - General:
diff --git a/README.CVS b/README.CVS
index fe55866..adad019 100644
--- a/README.CVS
+++ b/README.CVS
@@ -7,8 +7,8 @@
 To successfully compile GNU nano from CVS, you'll need the
 following packages:
 
-- autoconf (version >= 2.52)
-- automake (version >= 1.6, 1.7.x recommended)
+- autoconf (version >= 2.54)
+- automake (version >= 1.7)
 - gettext (version >= 0.11.5)
 - texinfo
 - cvs
diff --git a/configure.ac b/configure.ac
index 0be9c28..ce5c261 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,9 +24,10 @@
 AM_INIT_AUTOMAKE
 AM_CONFIG_HEADER([config.h:config.h.in])
 
-AC_PREREQ(2.52)
+AC_PREREQ(2.54)
 
 dnl Checks for programs.
+AC_GNU_SOURCE
 AC_PROG_CC
 AC_ISC_POSIX
 AC_SYS_LARGEFILE
@@ -270,7 +271,7 @@
     esac], [AC_MSG_RESULT(no)])
 
 dnl Checks for functions
-AC_CHECK_FUNCS(snprintf vsnprintf strcasecmp strncasecmp)
+AC_CHECK_FUNCS(snprintf vsnprintf isblank strcasecmp strncasecmp strcasestr)
 if test "x$ac_cv_func_snprintf" = "xno" -o "xac_cv_func_vsnprintf" = "xno"
 then
 	AM_PATH_GLIB_2_0(2.0.0,,
diff --git a/src/files.c b/src/files.c
index c00b4a2..bd75be9 100644
--- a/src/files.c
+++ b/src/files.c
@@ -189,7 +189,7 @@
 	   assume it's a DOS or Mac formatted file if it hasn't been
 	   detected as one already! */
 	if (fileformat == 0 && !ISSET(NO_CONVERT)
-		&& is_cntrl_char((int)input) != 0 && input != '\t'
+		&& is_cntrl_char(input) && input != '\t'
 		&& input != '\r' && input != '\n')
 	    SET(NO_CONVERT);
 #endif
@@ -2230,7 +2230,7 @@
 	tmp = matchbuf;
 
 	/* skip any leading white space */
-	while (*tmp && isspace((int)*tmp))
+	while (*tmp && isblank(*tmp))
 	    ++tmp;
 
 	/* Free up any memory already allocated */
diff --git a/src/nano.c b/src/nano.c
index 0238aa1..0d7a2dd 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1106,7 +1106,7 @@
 	int extra = 0;
 	const char *spc = current->data;
 
-	while (*spc == ' ' || *spc == '\t') {
+	while (isblank(*spc)) {
 	    extra++;
 	    spc++;
 	}
@@ -1312,14 +1312,14 @@
     wrap_line = inptr->data + i;
     for (; i < len; i++, wrap_line++) {
 	/* record where the last word ended */
-	if (*wrap_line != ' ' && *wrap_line != '\t')
+	if (!isblank(*wrap_line))
 	    word_back = i;
 	/* if we have found a "legal wrap point" and the current word
 	 * extends too far, then we stop */
 	if (wrap_loc != -1 && strnlenpt(inptr->data, word_back + 1) > fill)
 	    break;
 	/* we record the latest "legal wrap point" */
-	if (word_back != i && wrap_line[1] != ' ' && wrap_line[1] != '\t')
+	if (word_back != i && !isblank(wrap_line[1]))
 	    wrap_loc = i;
     }
     if (wrap_loc < 0 || i == len)
@@ -1387,7 +1387,7 @@
 	 * between after_break and wrap_line.  If the line already ends
 	 * in a tab or a space, we don't add a space and decrement
 	 * totsize to account for that. */
-	if (!isspace((int) newline[strlen(newline) - 1]))
+	if (!isblank(newline[strlen(newline) - 1]))
 	    strcat(newline, " ");
 	else
 	    totsize--;
@@ -1885,7 +1885,7 @@
     size_t len = 0;
 
     assert(line != NULL);
-    while (*line == ' ' || *line == '\t') {
+    while (isblank(*line)) {
 	line++;
 	len++;
     }
@@ -1917,7 +1917,7 @@
     assert(line != NULL);
     assert(line->data != NULL);
     assert(skip < strlen(line->data));
-    assert(line->data[skip] != ' ' && line->data[skip] != '\t');
+    assert(!isblank(line->data[skip]));
 
     back = line->data + skip;
     front = back;
@@ -2078,7 +2078,7 @@
 int breakable(const char *line, int goal)
 {
     for (; *line != '\0' && goal >= 0; line++) {
-	if (*line == ' ' || *line == '\t')
+	if (isblank(*line))
 	    return TRUE;
 
 	if (is_cntrl_char(*line) != 0)
@@ -2334,7 +2334,7 @@
 		 * characters, as searching for the end of the paragraph
 		 * does. */
 		for (i = 0; current->data[i] != '\0'; i++) {
-		    if (isspace(current->data[i]))
+		    if (isblank(current->data[i]))
 			j++;
 		    else {
 			i = 0;
diff --git a/src/nano.h b/src/nano.h
index bd2ca43..0f1c883 100644
--- a/src/nano.h
+++ b/src/nano.h
@@ -91,7 +91,12 @@
 # endif
 #endif
 
-/* If no strcasecmp() or strncasecmp(), use the versions we have. */
+/* If no isblank(), strcasecmp(), strncasecmp(), or strcasestr(), use
+ * the versions we have. */
+#ifndef HAVE_ISBLANK
+#define isblank is_blank_char
+#endif
+
 #ifndef HAVE_STRCASECMP
 #define strcasecmp nstricmp
 #endif
@@ -100,6 +105,10 @@
 #define strncasecmp nstrnicmp
 #endif
 
+#ifndef HAVE_STRCASESTR
+#define strcasestr nstristr
+#endif
+
 /* Assume ERR is defined as -1.  To avoid duplicate case values when
  * some key definitions are missing, we have to set all of these, and
  * all of the special sentinel values below, to different negative
diff --git a/src/proto.h b/src/proto.h
index 5effeef..895ac48 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -413,6 +413,9 @@
 #endif
 int regexp_bol_or_eol(const regex_t *preg, const char *string);
 #endif
+#ifndef HAVE_ISBLANK
+int is_blank_char(int c);
+#endif
 int is_cntrl_char(int c);
 int num_of_digits(int n);
 void align(char **strp);
diff --git a/src/rcfile.c b/src/rcfile.c
index 306faa0..4d28856 100644
--- a/src/rcfile.c
+++ b/src/rcfile.c
@@ -31,6 +31,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <pwd.h>
+#include <ctype.h>
 #include <assert.h>
 #include "proto.h"
 #include "nano.h"
@@ -131,7 +132,7 @@
 /* Parse the next word from the string.  Returns NULL if we hit EOL. */
 char *parse_next_word(char *ptr)
 {
-    while (*ptr != ' ' && *ptr != '\t' && *ptr != '\n' && *ptr != '\0')
+    while (!isblank(*ptr) && *ptr != '\n' && *ptr != '\0')
 	ptr++;
 
     if (*ptr == '\0')
@@ -140,7 +141,7 @@
     /* Null terminate and advance ptr */
     *ptr++ = 0;
 
-    while (*ptr == ' ' || *ptr == '\t')
+    while (isblank(*ptr))
 	ptr++;
 
     return ptr;
@@ -179,7 +180,7 @@
 	ptr = last_quote + 1;
     }
     if (ptr != NULL)
-	while (*ptr == ' ' || *ptr == '\t')
+	while (isblank(*ptr))
 	    ptr++;
     return ptr;
 }
@@ -237,7 +238,7 @@
     /* Null terminate and advance ptr. */
     *ptr++ = '\0';
 
-    while (*ptr == ' ' || *ptr == '\t')
+    while (isblank(*ptr))
 	ptr++;
 
     return ptr;
@@ -484,7 +485,7 @@
     while (fgets(buf, 1023, rcstream) != 0) {
 	lineno++;
 	ptr = buf;
-	while (*ptr == ' ' || *ptr == '\t')
+	while (isblank(*ptr))
 	    ptr++;
 
 	if (*ptr == '\n' || *ptr == '\0')
diff --git a/src/utils.c b/src/utils.c
index da41430..4e5cbe0 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -52,10 +52,20 @@
 }
 #endif /* HAVE_REGEX_H */
 
+#ifndef HAVE_ISBLANK
+/* This function is equivalent to isblank(). */
+int is_blank_char(int c)
+{
+    return (c == '\t' || c == ' ');
+}
+#endif
+
+/* This function is equivalent to iscntrl(), except in that it also
+ * handles control characters with their high bits set. */
 int is_cntrl_char(int c)
 {
     return (-128 <= c && c < -96) || (0 <= c && c < 32) ||
-		(127 <= c && c < 160);
+	(127 <= c && c < 160);
 }
 
 int num_of_digits(int n)
@@ -146,6 +156,7 @@
 }
 #endif
 
+#ifndef HAVE_STRCASESTR
 /* This function is equivalent to strcasestr().  It was adapted from
  * mutt's mutt_stristr() function. */
 const char *nstristr(const char *haystack, const char *needle)
@@ -165,6 +176,7 @@
 
     return NULL;
 }
+#endif
 
 /* None of this is needed if we're using NANO_SMALL! */
 #ifndef NANO_SMALL
@@ -256,7 +268,7 @@
     else if (ISSET(REVERSE_SEARCH))
 	return revstristr(haystack, needle, start);
 #endif
-    return nstristr(start, needle);
+    return strcasestr(start, needle);
 }
 
 /* This is a wrapper for the perror() function.  The wrapper takes care