diff --git a/endpoints/web.py b/endpoints/web.py
index 8376cbeaf..c3a1136d9 100644
--- a/endpoints/web.py
+++ b/endpoints/web.py
@@ -1,7 +1,7 @@
 import json
 import logging
 
-from base64 import urlsafe_b64encode
+from jwkest import long_to_base64
 from cachetools import lru_cache
 from cryptography.x509 import load_pem_x509_certificate
 from cryptography.hazmat.backends import default_backend
@@ -701,8 +701,8 @@ def jwk_set_uri():
       'kty': 'RSA',
       'alg': 'RS256',
       'use': 'sig',
-      'n': urlsafe_b64encode(str(certificate.public_numbers().n)),
-      'e': urlsafe_b64encode(str(certificate.public_numbers().e)),
+      'n': long_to_base64(certificate.public_numbers().n),
+      'e': long_to_base64(certificate.public_numbers().e),
     }],
     'issuer': JWT_ISSUER,
   })