diff --git a/tools/distrib/check_copyright.py b/tools/distrib/check_copyright.py
index f06e5f1d1a1..51852adfd33 100755
--- a/tools/distrib/check_copyright.py
+++ b/tools/distrib/check_copyright.py
@@ -92,9 +92,20 @@ LICENSE_PREFIX = {
   'LICENSE':    '',
 }
 
-KNOWN_BAD = set([
+_EXEMPT = frozenset((
+  # Generated protocol compiler output.
+  'examples/python/helloworld/helloworld_pb2.py',
+  'examples/python/helloworld/helloworld_pb2_grpc.py',
+  'examples/python/multiplex/helloworld_pb2.py',
+  'examples/python/multiplex/helloworld_pb2_grpc.py',
+  'examples/python/multiplex/route_guide_pb2.py',
+  'examples/python/multiplex/route_guide_pb2_grpc.py',
+  'examples/python/route_guide/route_guide_pb2.py',
+  'examples/python/route_guide/route_guide_pb2_grpc.py',
+
+  # An older file originally from outside gRPC.
   'src/php/tests/bootstrap.php',
-])
+))
 
 
 RE_YEAR = r'Copyright (?P<first_year>[0-9]+\-)?(?P<last_year>[0-9]+), Google Inc\.'
@@ -140,7 +151,8 @@ except subprocess.CalledProcessError:
   sys.exit(0)
 
 for filename in filename_list:
-  if filename in KNOWN_BAD: continue
+  if filename in _EXEMPT:
+    continue
   ext = os.path.splitext(filename)[1]
   base = os.path.basename(filename)
   if ext in RE_LICENSE: