diff --git a/terminator.h b/terminator.h
index 97c9d7f..e536d38 100644
--- a/terminator.h
+++ b/terminator.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_TERMINATOR_H__
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H__
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H_
 
 #include <signal.h>
 
@@ -50,4 +50,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H__
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_TERMINATOR_H_