diff --git a/quickjs.c b/quickjs.c
index 8c06b06..005e93b 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -54542,6 +54542,7 @@ JSValue JS_AceNewInstance(JSContext *ctx, int classId, int argc, JSValueConst *a
     JSValue proto = JS_GetClassProto(ctx, classId);
     JSValue ctor = JS_GetProperty(ctx, proto, JS_ATOM_constructor);
     JSValue newInst = JS_CallConstructor2(ctx, ctor, obj, argc, argv);
+    JS_SetPrototype(ctx, newInst, proto);
     JS_FreeValue(ctx, ctor);
     JS_FreeValue(ctx, proto);
     JS_FreeValue(ctx, obj);