diff --git a/frontend/src/components/FillModal.jsx b/frontend/src/components/FillModal.jsx
index 35afec2..0e60295 100644
--- a/frontend/src/components/FillModal.jsx
+++ b/frontend/src/components/FillModal.jsx
@@ -194,7 +194,7 @@ export default function FillModal({ template, onSubmit, onClose }) {
         template_id: template.id,
         title: template.name,
         values: taskValues,
-        file_path: (allowsFileUpload && uploadedFile) ? uploadedFile : null,
+        file_path: (allowsFileUpload && uploadedFile) ? uploadedFile : undefined,
       });
     } finally {
       setSubmitting(false);