diff --git a/lib/galaxy/tools/__init__.py b/lib/galaxy/tools/__init__.py
index d7dc68b5b7e1..1ba71eab3101 100644
--- a/lib/galaxy/tools/__init__.py
+++ b/lib/galaxy/tools/__init__.py
@@ -1282,7 +1282,7 @@ def parse_tests(self):
     def tests(self):
         if self.__tests:
             return [ToolTestDescription(d) for d in json.loads(self.__tests)]
-        return self.__tests
+        return None
 
     @property
     def _repository_dir(self):