diff --git a/action.yml b/action.yml
index d93585c..0c28e9b 100644
--- a/action.yml
+++ b/action.yml
@@ -147,7 +147,7 @@ runs:
         fi
 
         input_sync=${{inputs.sync}}
-        if [ "${{github.event_name}}" == "workflow_dispatch" ]; then
+        if [ "${{github.event_name}}" == "workflow_dispatch" ] && [ -n "${{github.event.inputs.sync}}" ]; then
           input_sync=${{github.event.inputs.sync}}
         fi