diff --git a/mjit.c b/mjit.c
index d3e18c112c..04bdf404b7 100644
--- a/mjit.c
+++ b/mjit.c
@@ -1237,6 +1237,7 @@ static void mjit_wait(struct rb_iseq_constant_body *body);
 static void
 check_unit_queue(void)
 {
+    if (mjit_opts.custom) return;
     if (worker_stopped) return;
     if (current_cc_pid != 0) return; // still compiling