diff --git a/include/r3_define.h b/include/r3_define.h
index bee91da..0808077 100644
--- a/include/r3_define.h
+++ b/include/r3_define.h
@@ -7,6 +7,7 @@
 
 #ifndef DEFINE_H
 #define DEFINE_H
+#include <stdbool.h>
 
 #ifndef bool
 typedef unsigned char bool;