diff --git a/lib/galaxy/webapps/galaxy/controllers/shed_tool_static.py b/lib/galaxy/webapps/galaxy/controllers/shed_tool_static.py
index bcc722f81db..042e8184f9c 100644
--- a/lib/galaxy/webapps/galaxy/controllers/shed_tool_static.py
+++ b/lib/galaxy/webapps/galaxy/controllers/shed_tool_static.py
@@ -53,4 +53,4 @@ class ShedToolStatic(BaseUIController):
                     trans.response.set_content_type(mime)
             return open(asset_path, 'rb')
         else:
-            return None
+            raise RequestParameterInvalidException()