diff --git a/mock_p2p_manager.h b/mock_p2p_manager.h
index 4d91765..353b904 100644
--- a/mock_p2p_manager.h
+++ b/mock_p2p_manager.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_MOCK_P2P_MANAGER_H__
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H__
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H_
 
 #include "fake_p2p_manager.h"
 
@@ -92,4 +92,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H__
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H_