diff --git a/sentry_auth_google/utils.py b/sentry_auth_google/utils.py
index 73740b3..a70b38c 100644
--- a/sentry_auth_google/utils.py
+++ b/sentry_auth_google/utils.py
@@ -5,4 +5,4 @@
 
 def urlsafe_b64decode(b64string):
     padded = b64string + b'=' * (4 - len(b64string) % 4)
-    return base64.urlsafe_b64decode(padded)
+    return base64.urlsafe_b64decode(str(padded))