diff --git a/google/oauth2/_client.py b/google/oauth2/_client.py
index 98d9599cf..8f4fe6d87 100644
--- a/google/oauth2/_client.py
+++ b/google/oauth2/_client.py
@@ -325,7 +325,7 @@ def call_iam_generate_id_token_endpoint(
     signer_email,
     audience,
     access_token,
-    universe_domain,
+    universe_domain = credentials.DEFAULT_UNIVERSE_DOMAIN,
 ):
     """Call iam.generateIdToken endpoint to get ID token.