diff --git a/Zend/Zend.m4 b/Zend/Zend.m4
index 47ea9c831d52..72bc116f7edb 100644
--- a/Zend/Zend.m4
+++ b/Zend/Zend.m4
@@ -317,6 +317,7 @@ int emu(const opcode_handler_t *ip, void *fp) {
   while ((*ip)());
   FP = orig_fp;
   IP = orig_ip;
+  return 0;
 }], [])],
   [php_cv_have_global_register_vars=yes],
   [php_cv_have_global_register_vars=no])