diff --git a/src/lj_dispatch.c b/src/lj_dispatch.c
index 8009d289..63e09752 100644
--- a/src/lj_dispatch.c
+++ b/src/lj_dispatch.c
@@ -292,9 +292,9 @@ int luaJIT_setmode(lua_State *L, int idx, int mode)
       } else {
 	return 0;  /* Failed. */
       }
-      g->bc_cfunc_ext = BCINS_AD(BC_FUNCCW, 0, 0);
+      setbc_op(&g->bc_cfunc_ext, BC_FUNCCW);
     } else {
-      g->bc_cfunc_ext = BCINS_AD(BC_FUNCC, 0, 0);
+      setbc_op(&g->bc_cfunc_ext, BC_FUNCC);
     }
     break;
   default: