diff --git a/client-src/utils/createSocketURL.js b/client-src/utils/createSocketURL.js
index b79d994829..5d8a28ddbd 100644
--- a/client-src/utils/createSocketURL.js
+++ b/client-src/utils/createSocketURL.js
@@ -5,7 +5,7 @@
 function format(objURL) {
   let protocol = objURL.protocol || "";
 
-  if (protocol && !protocol.endsWith(":")) {
+  if (protocol && protocol.substr(-1) !== ":") {
     protocol += ":";
   }