diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
index f6cb668782c6..2d3085fb454f 100644
--- a/dom/bindings/BindingUtils.cpp
+++ b/dom/bindings/BindingUtils.cpp
@@ -1898,10 +1898,11 @@ InterfaceHasInstance(JSContext* cx, JS::Handle<JSObject*> obj,
     return true;
   }
 
-  if (jsipc::IsWrappedCPOW(instance)) {
+  JS::Rooted<JSObject*> unwrapped(cx, js::CheckedUnwrap(instance, true));
+  if (unwrapped && jsipc::IsCPOW(unwrapped)) {
     bool boolp = false;
-    if (!jsipc::DOMInstanceOf(cx, js::CheckedUnwrap(instance), clasp->mPrototypeID,
-                              clasp->mDepth, &boolp)) {
+    if (!jsipc::DOMInstanceOf(cx, unwrapped, clasp->mPrototypeID,
+                                                clasp->mDepth, &boolp)) {
       return false;
     }
     *bp = boolp;
diff --git a/js/ipc/WrapperOwner.cpp b/js/ipc/WrapperOwner.cpp
index d418f89ee30c..942a0f4677d2 100644
--- a/js/ipc/WrapperOwner.cpp
+++ b/js/ipc/WrapperOwner.cpp
@@ -676,15 +676,6 @@ IsCPOW(JSObject *obj)
     return IsProxy(obj) && GetProxyHandler(obj) == &CPOWProxyHandler::singleton;
 }
 
-bool
-IsWrappedCPOW(JSObject *obj)
-{
-    JSObject *unwrapped = js::CheckedUnwrap(obj, true);
-    if (!unwrapped)
-        return false;
-    return IsCPOW(unwrapped);
-}
-
 nsresult
 InstanceOf(JSObject *proxy, const nsID *id, bool *bp)
 {
diff --git a/js/ipc/WrapperOwner.h b/js/ipc/WrapperOwner.h
index 5621646a1c83..26ce1adb8f19 100644
--- a/js/ipc/WrapperOwner.h
+++ b/js/ipc/WrapperOwner.h
@@ -144,9 +144,6 @@ class WrapperOwner : public virtual JavaScriptShared
 bool
 IsCPOW(JSObject *obj);
 
-bool
-IsWrappedCPOW(JSObject *obj);
-
 nsresult
 InstanceOf(JSObject *obj, const nsID *id, bool *bp);
 
diff --git a/js/xpconnect/src/XPCComponents.cpp b/js/xpconnect/src/XPCComponents.cpp
index 6e2d5c2b6fc7..26893dddb3eb 100644
--- a/js/xpconnect/src/XPCComponents.cpp
+++ b/js/xpconnect/src/XPCComponents.cpp
@@ -3113,7 +3113,7 @@ nsXPCComponents_Utils::IsCrossProcessWrapper(HandleValue obj, bool *out)
     if (obj.isPrimitive())
         return NS_ERROR_INVALID_ARG;
 
-    *out = jsipc::IsWrappedCPOW(&obj.toObject());
+    *out = jsipc::IsCPOW(js::CheckedUnwrap(&obj.toObject()));
     return NS_OK;
 }
 
diff --git a/js/xpconnect/src/XPCConvert.cpp b/js/xpconnect/src/XPCConvert.cpp
index 2d5f8901b2b7..4b5a1fe8e491 100644
--- a/js/xpconnect/src/XPCConvert.cpp
+++ b/js/xpconnect/src/XPCConvert.cpp
@@ -65,8 +65,8 @@ UnwrapNativeCPOW(nsISupports* wrapper)
 {
     nsCOMPtr<nsIXPConnectWrappedJS> underware = do_QueryInterface(wrapper);
     if (underware) {
-        JSObject *mainObj = underware->GetJSObject();
-        if (mainObj && mozilla::jsipc::IsWrappedCPOW(mainObj))
+        JSObject* mainObj = underware->GetJSObject();
+        if (mainObj && mozilla::jsipc::IsCPOW(mainObj))
             return mainObj;
     }
     return nullptr;
diff --git a/js/xpconnect/src/XPCWrappedJS.cpp b/js/xpconnect/src/XPCWrappedJS.cpp
index 35af471c36b6..d4520aafe4c6 100644
--- a/js/xpconnect/src/XPCWrappedJS.cpp
+++ b/js/xpconnect/src/XPCWrappedJS.cpp
@@ -12,7 +12,6 @@
 #include "nsCxPusher.h"
 #include "nsContentUtils.h"
 #include "nsThreadUtils.h"
-#include "JavaScriptParent.h"
 
 using namespace mozilla;
 
@@ -335,9 +334,7 @@ nsXPCWrappedJS::GetNewOrUsed(JS::HandleObject jsObj,
         return NS_ERROR_FAILURE;
     }
 
-    bool allowNonScriptable = mozilla::jsipc::IsWrappedCPOW(jsObj);
-    nsRefPtr<nsXPCWrappedJSClass> clasp = nsXPCWrappedJSClass::GetNewOrUsed(cx, aIID,
-                                                                            allowNonScriptable);
+    nsRefPtr<nsXPCWrappedJSClass> clasp = nsXPCWrappedJSClass::GetNewOrUsed(cx, aIID);
     if (!clasp)
         return NS_ERROR_FAILURE;
 
diff --git a/js/xpconnect/src/XPCWrappedJSClass.cpp b/js/xpconnect/src/XPCWrappedJSClass.cpp
index 62d6074654d2..a5b6e1d5b471 100644
--- a/js/xpconnect/src/XPCWrappedJSClass.cpp
+++ b/js/xpconnect/src/XPCWrappedJSClass.cpp
@@ -90,7 +90,7 @@ bool xpc_IsReportableErrorCode(nsresult code)
 
 // static
 already_AddRefed<nsXPCWrappedJSClass>
-nsXPCWrappedJSClass::GetNewOrUsed(JSContext* cx, REFNSIID aIID, bool allowNonScriptable)
+nsXPCWrappedJSClass::GetNewOrUsed(JSContext* cx, REFNSIID aIID)
 {
     XPCJSRuntime* rt = nsXPConnect::GetRuntimeInstance();
     IID2WrappedJSClassMap* map = rt->GetWrappedJSClassMap();
@@ -101,7 +101,7 @@ nsXPCWrappedJSClass::GetNewOrUsed(JSContext* cx, REFNSIID aIID, bool allowNonScr
         nsXPConnect::XPConnect()->GetInfoForIID(&aIID, getter_AddRefs(info));
         if (info) {
             bool canScript, isBuiltin;
-            if (NS_SUCCEEDED(info->IsScriptable(&canScript)) && (canScript || allowNonScriptable) &&
+            if (NS_SUCCEEDED(info->IsScriptable(&canScript)) && canScript &&
                 NS_SUCCEEDED(info->IsBuiltinClass(&isBuiltin)) && !isBuiltin &&
                 nsXPConnect::IsISupportsDescendant(info))
             {
@@ -202,14 +202,12 @@ nsXPCWrappedJSClass::CallQueryInterfaceOnJSObject(JSContext* cx,
     // implement intentionally (for security) unscriptable interfaces.
     // We so often ask for nsISupports that we can short-circuit the test...
     if (!aIID.Equals(NS_GET_IID(nsISupports))) {
-        bool allowNonScriptable = mozilla::jsipc::IsWrappedCPOW(jsobj);
-
         nsCOMPtr<nsIInterfaceInfo> info;
         nsXPConnect::XPConnect()->GetInfoForIID(&aIID, getter_AddRefs(info));
         if (!info)
             return nullptr;
         bool canScript, isBuiltin;
-        if (NS_FAILED(info->IsScriptable(&canScript)) || (!canScript && !allowNonScriptable) ||
+        if (NS_FAILED(info->IsScriptable(&canScript)) || !canScript ||
             NS_FAILED(info->IsBuiltinClass(&isBuiltin)) || isBuiltin)
             return nullptr;
     }
diff --git a/js/xpconnect/src/xpcprivate.h b/js/xpconnect/src/xpcprivate.h
index dfc90a65d7ea..2c67e23168c9 100644
--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -2241,8 +2241,7 @@ public:
 
     static already_AddRefed<nsXPCWrappedJSClass>
     GetNewOrUsed(JSContext* cx,
-                 REFNSIID aIID,
-                 bool allowNonScriptable = false);
+                 REFNSIID aIID);
 
     REFNSIID GetIID() const {return mIID;}
     XPCJSRuntime* GetRuntime() const {return mRuntime;}