diff --git a/internal/ceres/array_utils.h b/internal/ceres/array_utils.h
index 8f4d41b..bd51aa5 100644
--- a/internal/ceres/array_utils.h
+++ b/internal/ceres/array_utils.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
@@ -43,6 +43,7 @@
 #ifndef CERES_INTERNAL_ARRAY_UTILS_H_
 #define CERES_INTERNAL_ARRAY_UTILS_H_
 
+#include <cstdint>
 #include <string>
 
 #include "ceres/internal/disable_warnings.h"