diff --git a/openbox/mainloop.c b/openbox/mainloop.c
index f78f5b12..b2921207 100644
--- a/openbox/mainloop.c
+++ b/openbox/mainloop.c
@@ -530,6 +530,9 @@ void ob_main_loop_timeout_add(ObMainLoop *loop,
                               GDestroyNotify notify)
 {
     ObMainLoopTimer *t = g_new(ObMainLoopTimer, 1);
+
+    g_assert(microseconds > 0); /* if it's 0 it'll cause an infinite loop */
+
     t->delay = microseconds;
     t->func = handler;
     t->data = data;