diff --git a/action.h b/action.h
index 104ef9e..45c6430 100644
--- a/action.h
+++ b/action.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_ACTION_H__
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_ACTION_H__
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_ACTION_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_ACTION_H_
 
 #include <stdio.h>
 #include <tr1/memory>
@@ -200,4 +200,4 @@
 
 };  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_ACTION_H__
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_ACTION_H_