diff --git a/force_bdss/io/workflow_writer.py b/force_bdss/io/workflow_writer.py
index 1e5abca0d0c9df0c97c18e32e3bfa2e5053196d7..3a2eee725c519502759f240a7e29c554f1e0f458 100644
--- a/force_bdss/io/workflow_writer.py
+++ b/force_bdss/io/workflow_writer.py
@@ -17,7 +17,7 @@ class WorkflowWriter(HasStrictTraits):
             A file object on which to write the workflow, properly serialized
             into JSON.
         """
-        data = dict(version=1)
+        data = dict(version="1")
 
         data["workflow"] = self._workflow_data(workflow)
         json.dump(data, f)