diff --git a/test/mitmproxy/test_addonmanager.py b/test/mitmproxy/test_addonmanager.py
index accf48e0c..274d2d90c 100644
--- a/test/mitmproxy/test_addonmanager.py
+++ b/test/mitmproxy/test_addonmanager.py
@@ -137,6 +137,8 @@ def test_simple():
         a.trigger("custom")
         assert ta.custom_called
 
+        assert ta in a
+
 
 def test_load_option():
     o = options.Options()