diff --git a/autogen.sh b/autogen.sh
index de2559208a706cb63d8bf2002b5bab211eefc845..e1516e7b60093b1451862d599d7080967c21b987 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -7,6 +7,8 @@ gnulib_hash="4084b3a1094372b960ce4a97634e08f4538c8bdd"
 modules="
 	getdelim
 	getline
+	isblank
+	iswblank
 	strcase
 	strcasestr-simple
 	strnlen
diff --git a/configure.ac b/configure.ac
index 639b854159dc91d672c61c4a280ee2af3d411776..6f47eb7f0aecfd7447224400512c19e04d28caa6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -473,10 +473,10 @@ int main(void)
 
 dnl Checks for functions.
 
-AC_CHECK_FUNCS(isblank snprintf vsnprintf)
+AC_CHECK_FUNCS(snprintf vsnprintf)
 
 if test "x$enable_utf8" != xno; then
-    AC_CHECK_FUNCS(iswalnum iswblank iswpunct iswspace nl_langinfo mblen mbstowcs mbtowc wctomb wcwidth)
+    AC_CHECK_FUNCS(iswalnum iswpunct iswspace nl_langinfo mblen mbstowcs mbtowc wctomb wcwidth)
 fi
 
 if test x$ac_cv_func_snprintf = xno; then
diff --git a/src/chars.c b/src/chars.c
index add7a391854b8f7daf6a96af0c019870518b435d..3f80e31e7bcf225905e49d96ff63377e8b9ecc86 100644
--- a/src/chars.c
+++ b/src/chars.c
@@ -61,22 +61,6 @@ char *addstrings(char* str1, size_t len1, char* str2, size_t len2)
     return str1;
 }
 
-#ifndef HAVE_ISBLANK
-/* This function is equivalent to isblank(). */
-bool nisblank(int c)
-{
-    return isspace(c) && (c == '\t' || !is_cntrl_char(c));
-}
-#endif
-
-#if !defined(HAVE_ISWBLANK) && defined(ENABLE_UTF8)
-/* This function is equivalent to iswblank(). */
-bool niswblank(wchar_t wc)
-{
-    return iswspace(wc) && (wc == '\t' || !is_cntrl_wchar(wc));
-}
-#endif
-
 /* Return TRUE if the value of c is in byte range, and FALSE otherwise. */
 bool is_byte(int c)
 {
diff --git a/src/nano.h b/src/nano.h
index 82bb264cd7e80d6d12db2f4607b4a24ac73e40aa..d11e07bb5fd4458b847c80a52475f560c813cdbb 100644
--- a/src/nano.h
+++ b/src/nano.h
@@ -128,16 +128,6 @@
 #define vsnprintf g_vsnprintf
 #endif
 
-/* If no isblank(), iswblank(), strcasecmp(), strncasecmp(),
- * strcasestr(), strnlen(), getdelim(), or getline(), use the versions
- * we have. */
-#ifndef HAVE_ISBLANK
-#define isblank nisblank
-#endif
-#ifndef HAVE_ISWBLANK
-#define iswblank niswblank
-#endif
-
 /* If we aren't using ncurses with mouse support, turn the mouse support
  * off, as it's useless then. */
 #ifndef NCURSES_MOUSE_VERSION
diff --git a/src/proto.h b/src/proto.h
index 2891c86546819aedb750661f536a5e318661ffba..f139ad184371b69f3e07becf252e320702d039cc 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -193,12 +193,6 @@ void utf8_init(void);
 bool using_utf8(void);
 #endif
 char *addstrings(char* str1, size_t len1, char* str2, size_t len2);
-#ifndef HAVE_ISBLANK
-bool nisblank(int c);
-#endif
-#if !defined(HAVE_ISWBLANK) && defined(ENABLE_UTF8)
-bool niswblank(wchar_t wc);
-#endif
 bool is_byte(int c);
 bool is_alpha_mbchar(const char *c);
 bool is_alnum_mbchar(const char *c);