diff --git a/lib/js/runtime.sx b/lib/js/runtime.sx
index 8772d1e2..ba77a18f 100644
--- a/lib/js/runtime.sx
+++ b/lib/js/runtime.sx
@@ -2567,7 +2567,7 @@
           (and (>= idx 0) (< idx (len o)) (integer? idx))))
       (else false))))
 
-(define Object {:entries js-object-entries :defineProperties js-object-define-properties :__callable__ (fn (&rest args) (cond ((= (len args) 0) (dict)) (else (nth args 0)))) :preventExtensions js-object-prevent-extensions :prototype {} :values js-object-values :hasOwn js-object-has-own :freeze js-object-freeze :assign js-object-assign :isFrozen js-object-is-frozen :getOwnPropertyDescriptor js-object-get-own-property-descriptor :fromEntries js-object-from-entries :defineProperty js-object-define-property :setPrototypeOf js-object-set-prototype-of :getOwnPropertyNames js-object-get-own-property-names :getOwnPropertyDescriptors js-object-get-own-property-descriptors :create js-object-create :isExtensible js-object-is-extensible :is js-object-is :keys js-object-keys :getPrototypeOf js-object-get-prototype-of :isSealed js-object-is-sealed :seal js-object-seal})
+(define Object {:entries js-object-entries :defineProperties js-object-define-properties :__callable__ (fn (&rest args) (cond ((= (len args) 0) (dict)) (else (nth args 0)))) :preventExtensions js-object-prevent-extensions :prototype {:valueOf (fn () (js-this)) :propertyIsEnumerable (fn (k) (let ((o (js-this))) (js-object-has-own o k))) :isPrototypeOf (fn (o) (let ((this-val (js-this))) (cond ((not (dict? o)) false) (else (let ((proto (if (contains? (keys o) "__proto__") (get o "__proto__") nil))) (cond ((= proto this-val) true) ((= proto nil) false) (else ((get (get Object "prototype") "isPrototypeOf") proto)))))))) :toString (fn () "[object Object]") :hasOwnProperty (fn (k) (let ((o (js-this))) (js-object-has-own o k))) :toLocaleString (fn () "[object Object]")} :values js-object-values :hasOwn js-object-has-own :freeze js-object-freeze :assign js-object-assign :isFrozen js-object-is-frozen :getOwnPropertyDescriptor js-object-get-own-property-descriptor :fromEntries js-object-from-entries :defineProperty js-object-define-property :setPrototypeOf js-object-set-prototype-of :getOwnPropertyNames js-object-get-own-property-names :getOwnPropertyDescriptors js-object-get-own-property-descriptors :create js-object-create :isExtensible js-object-is-extensible :is js-object-is :keys js-object-keys :getPrototypeOf js-object-get-prototype-of :isSealed js-object-is-sealed :seal js-object-seal})
 
 (define
   js-delete-prop