diff --git a/omaha_response.h b/omaha_response.h
index 4d380a7..e704ee0 100644
--- a/omaha_response.h
+++ b/omaha_response.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_OMAHA_RESPONSE_H
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_RESPONSE_H
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_RESPONSE_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_RESPONSE_H_
 
 #include <fcntl.h>
 #include <sys/stat.h>
@@ -84,4 +84,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_RESPONSE_H
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_OMAHA_RESPONSE_H_