diff --git a/ports/macos/timer.c b/ports/macos/timer.c
index 0accdad14eea4b7bc2968d4d6cb8fc9edfb87dea..9ecea983f679fc59617d3b835e9ad8ec472ee905 100644
--- a/ports/macos/timer.c
+++ b/ports/macos/timer.c
@@ -38,6 +38,7 @@ static void timer_event_handler(struct aes67_timer * timer)
 void aes67_timer_init_system(void)
 {
     queue = dispatch_queue_create("timerQueue", 0);
+    assert(queue);
 }
 
 void aes67_timer_deinit_system(void)