diff --git a/pkgs/applications/version-management/gitlab/update.py b/pkgs/applications/version-management/gitlab/update.py
index 765f984fba5..26dc3d39eb1 100755
--- a/pkgs/applications/version-management/gitlab/update.py
+++ b/pkgs/applications/version-management/gitlab/update.py
@@ -115,6 +115,7 @@ def _update_data_json(filename: str, repo: GitLabRepo, rev: str, flavour: str):
             data = json.load(f)
             data[flavour] = flavour_data
             f.seek(0)
+            f.truncate()
             json.dump(data, f, indent=2)