diff --git a/src/converse-minimize.js b/src/converse-minimize.js
index 82402f0ec..ed6b962ae 100644
--- a/src/converse-minimize.js
+++ b/src/converse-minimize.js
@@ -358,7 +358,7 @@
                 });
             };
             converse.on('ready', onLogin);
-            converse.on('controlBoxOpened', function (chatbox) {
+            converse.on('controlBoxOpened', function (evt, chatbox) {
                 // Wrapped in anon method because at scan time, chatboxviews
                 // attr not set yet.
                 converse.chatboxviews.trimChats(chatbox);