diff --git a/functions/index.js b/functions/index.js
index a54eaef78..7328a12fc 100644
--- a/functions/index.js
+++ b/functions/index.js
@@ -61,6 +61,7 @@ function getAllUsers() {
 function isUsernameValid(name) {
   if (name === null || name === undefined || name === "") return false;
   if (/miodec/.test(name.toLowerCase())) return false;
+  if (/bitly/.test(name.toLowerCase())) return false;
   if (name.length > 12) return false;
   return /^[0-9a-zA-Z_.-]+$/.test(name);
 }