diff --git a/internal_packages/message-list/lib/message-toolbar-items.cjsx b/internal_packages/message-list/lib/message-toolbar-items.cjsx
index 40248c300..b95ba5ca2 100644
--- a/internal_packages/message-list/lib/message-toolbar-items.cjsx
+++ b/internal_packages/message-list/lib/message-toolbar-items.cjsx
@@ -33,6 +33,7 @@ class MessageToolbarItems extends React.Component
     @_unsubscribers.push FocusedContentStore.listen @_onChange
 
   componentWillUnmount: =>
+    return unless @_unsubscribers
     unsubscribe() for unsubscribe in @_unsubscribers
 
   _onChange: =>