Guard headers tool.
diff --git a/include/grpc/grpc_http.h b/include/grpc/grpc_http.h
index 757f53f..c41e874 100644
--- a/include/grpc/grpc_http.h
+++ b/include/grpc/grpc_http.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef __GRPC_GRPC_HTTP_H__
-#define __GRPC_GRPC_HTTP_H__
+#ifndef GRPC_GRPC_HTTP_H
+#define GRPC_GRPC_HTTP_H
 
 #ifdef __cplusplus
 extern "C" {
@@ -64,4 +64,4 @@
 }
 #endif
 
-#endif /* __GRPC_GRPC_HTTP_H__ */
+#endif  /* GRPC_GRPC_HTTP_H */