diff --git a/shared/nm-test-utils-impl.c b/shared/nm-test-utils-impl.c
index 0805d0b946..43176f4c7e 100644
--- a/shared/nm-test-utils-impl.c
+++ b/shared/nm-test-utils-impl.c
@@ -127,7 +127,7 @@ nmtstc_service_init (void)
 		g_source_attach (timeout_source, context);
 
 		child_source = g_child_watch_source_new (info->pid);
-		g_source_set_callback (child_source, (GSourceFunc)(void (*) (void)) _service_init_wait_child_wait, &data, NULL);
+		g_source_set_callback (child_source, G_SOURCE_FUNC (_service_init_wait_child_wait), &data, NULL);
 		g_source_attach (child_source, context);
 
 		had_timeout = !nmtst_main_loop_run (data.mainloop, 30000);