diff --git a/qfieldcloud_sdk/sdk.py b/qfieldcloud_sdk/sdk.py
index d477f70..9b10eef 100644
--- a/qfieldcloud_sdk/sdk.py
+++ b/qfieldcloud_sdk/sdk.py
@@ -427,7 +427,7 @@ def get_project_seed_xlsform(
         self,
         project_id: str,
         destination_dir: str,
-    ) -> str | None:
+    ) -> Optional[str]:
         """Get project seed XLSForm file content.
 
         Args: