diff --git a/kqueue.c b/kqueue.c
index 3558b9c4..4a8991d4 100644
--- a/kqueue.c
+++ b/kqueue.c
@@ -122,6 +122,27 @@ kq_init(void)
 	}
 	kqueueop->nevents = NEVENT;
 
+	/* Check for Mac OS X kqueue bug. */
+	kqueueop->changes[0].ident = -1;
+	kqueueop->changes[0].filter = EVFILT_READ;
+	kqueueop->changes[0].flags = EV_ADD;
+	/* 
+	 * If kqueue works, then kevent will succeed, and it will
+	 * stick an error in events[0].  If kqueue is broken, then
+	 * kevent will fail.
+	 */
+	if (kevent(kq,
+		kqueueop->changes, 1, kqueueop->events, NEVENT, NULL) != 1 ||
+	    kqueueop->events[0].ident != -1 ||
+	    kqueueop->events[0].flags != EV_ERROR) {
+		event_warn("%s: detected broken kqueue; not using.", __func__);
+		free(kqueueop->changes);
+		free(kqueueop->events);
+		free(kqueueop);
+		close(kq);
+		return (NULL);
+	}
+
 	return (kqueueop);
 }