diff --git a/src/lib/isURL.js b/src/lib/isURL.js
index 7529f4bde..a317b81d5 100644
--- a/src/lib/isURL.js
+++ b/src/lib/isURL.js
@@ -85,7 +85,7 @@ export default function isURL(url, options) {
   split = url.split('://');
   if (split.length > 1) {
     protocol = split.shift().toLowerCase();
-    if (options.require_valid_protocol && options.protocols.indexOf(protocol) === -1) {
+    if (options.require_valid_protocol && !protocol) {
       return false;
     }
   } else if (options.require_protocol) {