diff --git a/src/connectors/duo.ts b/src/connectors/duo.ts
index 1c0fb8d4ce..f31011987b 100644
--- a/src/connectors/duo.ts
+++ b/src/connectors/duo.ts
@@ -12,6 +12,12 @@ document.addEventListener('DOMContentLoaded', event => {
 
     const hostParam = getQsParam('host');
     const requestParam = getQsParam('request');
+
+    var hostUrl = new URL('https://' + hostParam);
+    if (!hostUrl.hostname.endsWith('.duosecurity.com') && !hostUrl.hostname.endsWith('.duofederal.com')) {
+        return;
+    }
+
     DuoWebSDK.init({
         iframe: 'duo_iframe',
         host: hostParam,