diff --git a/include/mruby/compile.h b/include/mruby/compile.h
index c22f8079a..4f9c49191 100644
--- a/include/mruby/compile.h
+++ b/include/mruby/compile.h
@@ -5,7 +5,7 @@
 */
 
 #ifndef MRUBY_COMPILE_H
-#define MRUBY_COMPILE_H 1
+#define MRUBY_COMPILE_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/mruby/data.h b/include/mruby/data.h
index f0420a0c6..8b1b5edb7 100644
--- a/include/mruby/data.h
+++ b/include/mruby/data.h
@@ -5,7 +5,7 @@
 */
 
 #ifndef MRUBY_DATA_H
-#define MRUBY_DATA_H 1
+#define MRUBY_DATA_H
 
 #if defined(__cplusplus)
 extern "C" {