diff --git a/subprocess.h b/subprocess.h
index c55b090..9e64806 100644
--- a/subprocess.h
+++ b/subprocess.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_SUBPROCESS_H__
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_SUBPROCESS_H__
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_SUBPROCESS_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_SUBPROCESS_H_
 
 #include <map>
 #include <string>
@@ -104,4 +104,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_SUBPROCESS_H__
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_SUBPROCESS_H_