diff --git a/kms/attestations/verify_attestation.py b/kms/attestations/verify_attestation.py
index d56242b0194b..cb296712f730 100644
--- a/kms/attestations/verify_attestation.py
+++ b/kms/attestations/verify_attestation.py
@@ -31,7 +31,7 @@
 import pem
 
 
-def verify(attestation_file, bundle_file):
+def verify(attestation_file: str, bundle_file: str):bool
     """Verifies an attestation using a bundle of certificates.
 
     Args: