diff --git a/app/api.js b/app/api.js
index b47ee84e..3d394c46 100644
--- a/app/api.js
+++ b/app/api.js
@@ -135,7 +135,7 @@ async function upload(stream, metadata, verifierB64, onprogress, canceller) {
   const endpoint =
     window.location.protocol === 'file:'
       ? 'wss://send2.dev.lcip.org/api/ws'
-      : `${protocol}//${host}:${port}/api/ws`;
+      : `${protocol}//${host}${port ? ':' : ''}${port}/api/ws`;
 
   const ws = await asyncInitWebSocket(endpoint);