Guard headers tool.
diff --git a/include/grpc/support/time.h b/include/grpc/support/time.h
index 150b7ac..1fd3181 100644
--- a/include/grpc/support/time.h
+++ b/include/grpc/support/time.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef __GRPC_SUPPORT_TIME_H__
-#define __GRPC_SUPPORT_TIME_H__
+#ifndef GRPC_SUPPORT_TIME_H
+#define GRPC_SUPPORT_TIME_H
 /* Time support.
    We use gpr_timespec, which is analogous to struct timespec.  On some
    machines, absolute times may be in local time.  */
@@ -100,4 +100,4 @@
 }
 #endif
 
-#endif /* __GRPC_SUPPORT_TIME_H__ */
+#endif  /* GRPC_SUPPORT_TIME_H */