diff --git a/google/auth/jwt.py b/google/auth/jwt.py
index 361c456..06e7679 100644
--- a/google/auth/jwt.py
+++ b/google/auth/jwt.py
@@ -42,7 +42,8 @@
 
 try:
     from collections.abc import Mapping
-except ImportError: # Python 2.7 compatibility
+# Python 2.7 compatibility
+except ImportError:  # pragma: NO COVER
     from collections import Mapping
 import copy
 import datetime