diff --git a/cf/broken-realloc.m4 b/cf/broken-realloc.m4
index 078891559..b6d962ace 100644
--- a/cf/broken-realloc.m4
+++ b/cf/broken-realloc.m4
@@ -10,7 +10,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <stddef.h>
 #include <stdlib.h>
 
-int main()
+int main(int argc, char **argv)
 {
 	return realloc(NULL, 17) == NULL;
 }
diff --git a/cf/broken-snprintf.m4 b/cf/broken-snprintf.m4
index 5f35517fa..653697e4b 100644
--- a/cf/broken-snprintf.m4
+++ b/cf/broken-snprintf.m4
@@ -6,7 +6,7 @@ ac_cv_func_snprintf_working=yes
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <stdio.h>
 #include <string.h>
-int main()
+int main(int argc, char **argv)
 {
 	char foo[[3]];
 	snprintf(foo, 2, "12");
diff --git a/cf/check-compile-et.m4 b/cf/check-compile-et.m4
index 736073d31..54d4fbad2 100644
--- a/cf/check-compile-et.m4
+++ b/cf/check-compile-et.m4
@@ -32,7 +32,7 @@ if ${COMPILE_ET} conftest_et.et >/dev/null 2>&1; then
 #include <com_err.h>
 #include <string.h>
 #include "conftest_et.h"
-int main(){
+int main(int argc, char **argv){
 #ifndef ERROR_TABLE_BASE_conf
 #error compile_et does not handle error_table N M
 #endif
diff --git a/cf/check-getpwnam_r-posix.m4 b/cf/check-getpwnam_r-posix.m4
index 8d2f45ae7..69bc06e7c 100644
--- a/cf/check-getpwnam_r-posix.m4
+++ b/cf/check-getpwnam_r-posix.m4
@@ -11,7 +11,7 @@ if test "$ac_cv_func_getpwnam_r" = yes; then
 	AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #define _POSIX_PTHREAD_SEMANTICS
 #include <pwd.h>
-int main()
+int main(int argc, char **argv)
 {
 	struct passwd pw, *pwd;
 	return getpwnam_r("", &pw, NULL, 0, &pwd) < 0;
diff --git a/cf/check-x.m4 b/cf/check-x.m4
index 873bd5120..5d8806c4b 100644
--- a/cf/check-x.m4
+++ b/cf/check-x.m4
@@ -34,11 +34,11 @@ if test "$no_x" != yes; then
 		LIBS="$ac_save_libs $foo $X_PRE_LIBS -lX11 $X_EXTRA_LIBS"
 		AC_RUN_IFELSE([
 		#include <X11/Xlib.h>
-		foo()
+		foo(void)
 		{
 		XOpenDisplay(NULL);
 		}
-		main()
+		main(int argc, char **argv)
 		{
 		return 0;
 		}
diff --git a/cf/have-pragma-weak.m4 b/cf/have-pragma-weak.m4
index 50af68846..cd892bd0e 100644
--- a/cf/have-pragma-weak.m4
+++ b/cf/have-pragma-weak.m4
@@ -16,11 +16,11 @@ cat > conftest_bar.$ac_ext <<'EOF'
 #include "confdefs.h"
 extern int foo;
 
-int t() {
+int t(void) {
   return foo;
 }
 
-int main() {
+int main(int argc, char **argv) {
   return t();
 }
 EOF
diff --git a/cf/telnet.m4 b/cf/telnet.m4
index af7a8d92a..637c66f44 100644
--- a/cf/telnet.m4
+++ b/cf/telnet.m4
@@ -35,7 +35,7 @@ case "$host" in
 			#include <stdio.h>
 			#include <errno.h>
 
-			int main()
+			int main(int argc, char **argv)
 			{
 			  int ret;
 			  ret = getmsg(open("/dev/null", 0), NULL, NULL, NULL);