diff --git a/src/Jackett.Common/Content/custom.js b/src/Jackett.Common/Content/custom.js
index 295b960d2..a56798638 100644
--- a/src/Jackett.Common/Content/custom.js
+++ b/src/Jackett.Common/Content/custom.js
@@ -1229,7 +1229,7 @@ function bindUIButtons() {
 }
 
 function proxyWarning(input) {
-    if (input.trim() != "")
+    if (input && input.trim() != "")
         $('#proxy-warning').show();
     else
         $('#proxy-warning').hide();