diff --git a/libmapper/mapper.h b/libmapper/mapper.h
index 7459e15..9f85c5f 100644
--- a/libmapper/mapper.h
+++ b/libmapper/mapper.h
@@ -1,3 +1,4 @@
+#include <stdbool.h>
 #include <systemd/sd-bus.h>
 #include <systemd/sd-event.h>
 
@@ -8,7 +9,8 @@
 void mapper_wait_async_free(mapper_async_wait *);
 
 int mapper_wait_async(sd_bus *, sd_event *, char *[],
-		void (*)(int, void *), void *, mapper_async_wait **);
+		void (*)(int, void *), void *, mapper_async_wait **,
+		bool);
 int mapper_get_service(sd_bus *conn, const char *obj, char **service);
 int mapper_get_object(sd_bus *conn, const char *obj, sd_bus_message **reply);
 #ifdef __cplusplus