diff --git a/cf/c-function.m4 b/cf/c-function.m4
index 1396f86f9..74ffd9511 100644
--- a/cf/c-function.m4
+++ b/cf/c-function.m4
@@ -12,12 +12,12 @@ AC_CACHE_VAL(ac_cv___function__, [
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <string.h>
 
-static char *foo()
+static char *foo(void)
 {
   return __FUNCTION__;
 }
 
-int main()
+int main(int argc, char **argc)
 {
   return strcmp(foo(), "foo") != 0;
 }
diff --git a/cf/check-var.m4 b/cf/check-var.m4
index 664ef20fc..f81f3524c 100644
--- a/cf/check-var.m4
+++ b/cf/check-var.m4
@@ -6,11 +6,11 @@ AC_MSG_CHECKING(for $1)
 AC_CACHE_VAL(ac_cv_var_$1, [
 m4_ifval([$2],[
 	AC_LINK_IFELSE([AC_LANG_PROGRAM([[$2
-	void * foo() { return &$1; }]],[[foo()]])],
+	void * foo(void) { return &$1; }]],[[foo()]])],
 	    [ac_cv_var_$1=yes],[ac_cv_var_$1=no])])
 if test "$ac_cv_var_$1" != yes ; then
 AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern int $1;
-int foo() { return $1; }]],[[foo()]])],
+int foo(void) { return $1; }]],[[foo()]])],
 	    [ac_cv_var_$1=yes],[ac_cv_var_$1=no])
 fi
 ])