diff --git a/configure b/configure
index 7b5952fa..51d81ca3 100755
--- a/configure
+++ b/configure
@@ -3530,175 +3530,9 @@ echo "$as_me: error: Cannot find required header file sys/ipc.h; XCurses cannot
 fi
 
 
-
-echo "$as_me:$LINENO: checking for ANSI C header files" >&5
-echo $ECHO_N "checking for ANSI C header files... $ECHO_C" >&6
-if test "${ac_cv_header_stdc+set}" = set; then
-  echo $ECHO_N "(cached) $ECHO_C" >&6
-else
-  cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-#include <stdlib.h>
-#include <stdarg.h>
-#include <string.h>
-#include <float.h>
-
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-rm -f conftest.$ac_objext
-if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
-  (eval $ac_compile) 2>conftest.er1
-  ac_status=$?
-  grep -v '^ *+' conftest.er1 >conftest.err
-  rm -f conftest.er1
-  cat conftest.err >&5
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } &&
-	 { ac_try='test -z "$ac_c_werror_flag"			 || test ! -s conftest.err'
-  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); }; } &&
-	 { ac_try='test -s conftest.$ac_objext'
-  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); }; }; then
-  ac_cv_header_stdc=yes
-else
-  echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-ac_cv_header_stdc=no
-fi
-rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
-
-if test $ac_cv_header_stdc = yes; then
-  # SunOS 4.x string.h does not declare mem*, contrary to ANSI.
-  cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-#include <string.h>
-
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "memchr" >/dev/null 2>&1; then
-  :
-else
-  ac_cv_header_stdc=no
-fi
-rm -f conftest*
-
-fi
-
-if test $ac_cv_header_stdc = yes; then
-  # ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
-  cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-#include <stdlib.h>
-
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "free" >/dev/null 2>&1; then
-  :
-else
-  ac_cv_header_stdc=no
-fi
-rm -f conftest*
-
-fi
-
-if test $ac_cv_header_stdc = yes; then
-  # /bin/cc in Irix-4.0.5 gets non-ANSI ctype macros unless using -ansi.
-  if test "$cross_compiling" = yes; then
-  :
-else
-  cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-#include <ctype.h>
-#if ((' ' & 0x0FF) == 0x020)
-# define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
-# define TOUPPER(c) (ISLOWER(c) ? 'A' + ((c) - 'a') : (c))
-#else
-# define ISLOWER(c) \
-		   (('a' <= (c) && (c) <= 'i') \
-		     || ('j' <= (c) && (c) <= 'r') \
-		     || ('s' <= (c) && (c) <= 'z'))
-# define TOUPPER(c) (ISLOWER(c) ? ((c) | 0x40) : (c))
-#endif
-
-#define XOR(e, f) (((e) && !(f)) || (!(e) && (f)))
-int
-main ()
-{
-  int i;
-  for (i = 0; i < 256; i++)
-    if (XOR (islower (i), ISLOWER (i))
-	|| toupper (i) != TOUPPER (i))
-      exit(2);
-  exit (0);
-}
-_ACEOF
-rm -f conftest$ac_exeext
-if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
-  (eval $ac_link) 2>&5
-  ac_status=$?
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
-  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); }; }; then
-  :
-else
-  echo "$as_me: program exited with status $ac_status" >&5
-echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-( exit $ac_status )
-ac_cv_header_stdc=no
-fi
-rm -f core *.core gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
-fi
-fi
-fi
-echo "$as_me:$LINENO: result: $ac_cv_header_stdc" >&5
-echo "${ECHO_T}$ac_cv_header_stdc" >&6
-if test $ac_cv_header_stdc = yes; then
-
-cat >>confdefs.h <<\_ACEOF
-#define STDC_HEADERS 1
-_ACEOF
-
-fi
-
 if test $ac_cv_header_stdc != yes; then
-	{ { echo "$as_me:$LINENO: error: Need ANSI C compiler" >&5
-echo "$as_me: error: Need ANSI C compiler" >&2;}
+	{ { echo "$as_me:$LINENO: error: Need ANSI C headers" >&5
+echo "$as_me: error: Need ANSI C headers" >&2;}
    { (exit 1); exit 1; }; }
 fi
 
@@ -3711,11 +3545,9 @@ fi
 
 
 for ac_header in fcntl.h \
-	limits.h \
 	time.h \
 	sys/time.h \
 	sys/select.h \
-	unistd.h \
 	dlfcn.h \
 	dl.h \
 	errno.h
@@ -4869,7 +4701,6 @@ done
 
 
 
-
 echo "$as_me:$LINENO: checking for location of X headers" >&5
 echo $ECHO_N "checking for location of X headers... $ECHO_C" >&6
 mh_x11_dir=""
@@ -5734,7 +5565,7 @@ echo "$as_me:$LINENO: checking compiler flags for a dynamic object" >&5
 echo $ECHO_N "checking compiler flags for a dynamic object... $ECHO_C" >&6
 
 cat > conftest.$ac_ext <<EOF
-#line 5737 "configure"
+#line 5568 "configure"
 int a=0
 EOF
 
@@ -5773,7 +5604,7 @@ echo "${ECHO_T}none of $mh_cv_flags supported" >&6
 
 mh_compile='${CC-cc} -c $DYN_COMP conftest.$ac_ext 1>&5'
 cat > conftest.$ac_ext <<EOF
-#line 5776 "configure"
+#line 5607 "configure"
 int foo()
 {
 return(0);
diff --git a/configure.ac b/configure.ac
index c54db850..d98ebfa5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -62,19 +62,16 @@ AC_PROG_MAKE_SET
 dnl ensure that the system has System V IPC support
 MH_IPC
 
+if test $ac_cv_header_stdc != yes; then
+	AC_MSG_ERROR([Need ANSI C headers])
+fi
+
 dnl Checks for libraries.
 
-dnl Checks for header files.
-AC_HEADER_STDC
-if test $ac_cv_header_stdc != yes; then
-	AC_MSG_ERROR([Need ANSI C compiler])
-fi
 AC_CHECK_HEADERS(fcntl.h \
-	limits.h \
 	time.h \
 	sys/time.h \
 	sys/select.h \
-	unistd.h \
 	dlfcn.h \
 	dl.h \
 	errno.h