diff --git a/contrib/sendmail/include/libmilter/mfapi.h b/contrib/sendmail/include/libmilter/mfapi.h
index 8e3a1732861..f56992f4c03 100644
--- a/contrib/sendmail/include/libmilter/mfapi.h
+++ b/contrib/sendmail/include/libmilter/mfapi.h
@@ -96,6 +96,8 @@ typedef int	sfsistat;
 #  ifndef bool
 #   ifndef __bool_true_false_are_defined
 typedef int	bool;
+#    define false	0
+#    define true	1
 #    define __bool_true_false_are_defined	1
 #   endif /* ! __bool_true_false_are_defined */
 #  endif /* bool */