diff --git a/examples/pgm_image.h b/examples/pgm_image.h
index 3d2df63..033ab4d 100644
--- a/examples/pgm_image.h
+++ b/examples/pgm_image.h
@@ -1,5 +1,5 @@
 // Ceres Solver - A fast non-linear least squares minimizer
-// Copyright 2015 Google Inc. All rights reserved.
+// Copyright 2023 Google Inc. All rights reserved.
 // http://ceres-solver.org/
 //
 // Redistribution and use in source and binary forms, with or without
@@ -43,8 +43,7 @@
 
 #include "glog/logging.h"
 
-namespace ceres {
-namespace examples {
+namespace ceres::examples {
 
 template <typename Real>
 class PGMImage {
@@ -311,7 +310,6 @@
   return data_;
 }
 
-}  // namespace examples
-}  // namespace ceres
+}  // namespace ceres::examples
 
 #endif  // CERES_EXAMPLES_PGM_IMAGE_H_