diff --git a/certbot/plugins/util_test.py b/certbot/plugins/util_test.py
index dcb21e037..cb17cebe2 100644
--- a/certbot/plugins/util_test.py
+++ b/certbot/plugins/util_test.py
@@ -105,9 +105,9 @@ def skipUnless(condition, reason):
     if hasattr(unittest, "skipUnless"):
         return unittest.skipUnless(condition, reason)
     elif condition:
-        return lambda x: x
+        return lambda cls: cls
     else:
-        return lambda x: None
+        return lambda cls: None
 
 
 @skipUnless(psutil_available(), "optional dependency psutil is not available")