diff --git a/src/main.coffee b/src/main.coffee
index 02650cce5..7cf9ab4af 100644
--- a/src/main.coffee
+++ b/src/main.coffee
@@ -464,6 +464,9 @@ Main =
       Main.callbackNodes Thread, threads
       Main.callbackNodes Post, posts
 
+    if $.hasClass d.body, 'fourchan_x'
+      alert '4chan X v2 detected: Disable it or v3 will break.'
+
     $.event '4chanXInitFinished'
     Main.checkUpdate()