1 files changed, 1 insertions, 1 deletions
diff --git a/scripts-dev/sign_json.py b/scripts-dev/sign_json.py
index 9459543106..bb217799fb 100755
--- a/scripts-dev/sign_json.py
+++ b/scripts-dev/sign_json.py
@@ -27,7 +27,7 @@ from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.util import json_encoder
 
 
-def main():
+def main() -> None:
     parser = argparse.ArgumentParser(
         description="""Adds a signature to a JSON object.