diff --git a/pyface/ui/qt4/util/gui_test_assistant.py b/pyface/ui/qt4/util/gui_test_assistant.py
index 857063f28..b585f728f 100644
--- a/pyface/ui/qt4/util/gui_test_assistant.py
+++ b/pyface/ui/qt4/util/gui_test_assistant.py
@@ -199,7 +199,7 @@ def assertTraitChangesInEventLoop(self, obj, trait, condition, count=1,
             change does not occur.
         """
         condition_ = lambda: condition(obj)
-        collector = TraitsChangeCollector(obj=obj, trait=trait)
+        collector = TraitsChangeCollector(obj=obj, trait_name=trait)
 
         collector.start_collecting()
         try: