diff --git a/src/microhttpd/connection.c b/src/microhttpd/connection.c
index e49bfe9a..0d7ba27b 100644
--- a/src/microhttpd/connection.c
+++ b/src/microhttpd/connection.c
@@ -4234,6 +4234,17 @@ MHD_queue_response (struct MHD_Connection *connection,
     return MHD_NO;
   }
 #endif /* UPGRADE_SUPPORT */
+  if ( (100 > (status_code & (~MHD_ICY_FLAG))) ||
+       (999 < (status_code & (~MHD_ICY_FLAG))) )
+  {
+#ifdef HAVE_MESSAGES
+    MHD_DLOG (daemon,
+              _ ("Refused wrong status code (%u). " \
+                 "HTTP required three digits status code!\n"),
+              (status_code & (~MHD_ICY_FLAG)));
+#endif
+    return MHD_NO;
+  }
   MHD_increment_response_rc (response);
   connection->response = response;
   connection->responseCode = status_code;