diff --git a/include/r3_define.h b/include/r3_define.h
index 6951b4d..5fd30ed 100644
--- a/include/r3_define.h
+++ b/include/r3_define.h
@@ -9,7 +9,7 @@
 #define DEFINE_H
 #include <stdbool.h>
 
-#ifndef bool
+#if !defined(bool) && !defined(__cplusplus)
 typedef unsigned char bool;
 #endif
 #ifndef FALSE