diff --git a/lib/galaxy/workflow/run_request.py b/lib/galaxy/workflow/run_request.py
index b4126a36713..f960d9d0dcd 100644
--- a/lib/galaxy/workflow/run_request.py
+++ b/lib/galaxy/workflow/run_request.py
@@ -288,6 +288,8 @@ def build_workflow_run_configs(trans, workflow, payload):
         steps_by_id = workflow.steps_by_id
         # Set workflow inputs.
         for key, input_dict in normalized_inputs.items():
+            if input_dict is None:
+                continue
             step = steps_by_id[key]
             if step.type == 'parameter_input':
                 continue