diff --git a/src/lib_jit.c b/src/lib_jit.c
index 921b84c8..868f697c 100644
--- a/src/lib_jit.c
+++ b/src/lib_jit.c
@@ -199,6 +199,7 @@ LJLIB_CF(jit_util_funcinfo)
     lua_setfield(L, -2, "source");
     lj_debug_pushloc(L, pt, pc);
     lua_setfield(L, -2, "loc");
+    setprotoV(L, lj_tab_setstr(L, t, lj_str_newlit(L, "proto")), pt);
   } else {
     GCfunc *fn = funcV(L->base);
     GCtab *t;