diff --git a/ext/gd/config.m4 b/ext/gd/config.m4
index ba1583e537d6e..73ad8f1a4e40f 100644
--- a/ext/gd/config.m4
+++ b/ext/gd/config.m4
@@ -162,17 +162,22 @@ AC_CACHE_CHECK([for working gdImageCreateFrom$1 in libgd], [php_var],
 
 /* A custom gdErrorMethod */
 void exit1(int priority, const char *format, va_list args) {
+  (void)priority;
+  (void)format;
+  (void)args;
   _exit(1);
 }
 
 /* Override the default gd_error_method with one that
    actually causes the program to return an error. */
-int main(int argc, char** argv) {
+int main(void)
+{
   m4_if([$1],[Xpm],
   [char* f = "test.xpm"],
   [FILE* f = NULL]);
   gdSetErrorMethod(exit1);
   gdImagePtr p = gdImageCreateFrom$1(f);
+  (void)p;
   return 0;
 }])],
   [AS_VAR_SET([php_var], [yes])],