diff --git a/include/stdbool.h b/include/stdbool.h
index 6ed13a6..d2ee446 100644
--- a/include/stdbool.h
+++ b/include/stdbool.h
@@ -6,5 +6,6 @@
 #define bool	_Bool
 #define true	1
 #define false	0
+#define __bool_true_false_are_defined 1
 
 #endif /* _STDBOOL_H */