diff --git a/lib/galaxy/workflow/modules.py b/lib/galaxy/workflow/modules.py
index 468f3cfff8a..b30fce45ffd 100644
--- a/lib/galaxy/workflow/modules.py
+++ b/lib/galaxy/workflow/modules.py
@@ -282,7 +282,7 @@ class SubWorkflowModule( WorkflowModule ):
                     name=name,
                     label=name,
                     multiple=False,
-                    extensions="input",
+                    extensions=["data"],
                     input_type=step_to_input_type[step_type],
                 )
                 inputs.append(input)