diff --git a/js/src/jsobj.cpp b/js/src/jsobj.cpp
index 23137fffcb27..7b97952889d3 100644
--- a/js/src/jsobj.cpp
+++ b/js/src/jsobj.cpp
@@ -1260,9 +1260,11 @@ NewObjectGCKind(const js::Class *clasp)
 }
 
 static inline JSObject *
-NewObject(ExclusiveContext *cx, const Class *clasp, types::TypeObject *type_, JSObject *parent,
-          gc::AllocKind kind, NewObjectKind newKind)
+NewObject(ExclusiveContext *cx, types::TypeObject *type_, JSObject *parent, gc::AllocKind kind,
+          NewObjectKind newKind)
 {
+    const Class *clasp = type_->clasp();
+
     JS_ASSERT(clasp != &ArrayObject::class_);
     JS_ASSERT_IF(clasp == &JSFunction::class_,
                  kind == JSFunction::FinalizeKind || kind == JSFunction::ExtendedFinalizeKind);
@@ -1365,7 +1367,7 @@ js::NewObjectWithGivenProto(ExclusiveContext *cxArg, const js::Class *clasp,
     if (!parent && proto.isObject())
         parent = proto.toObject()->getParent();
 
-    RootedObject obj(cxArg, NewObject(cxArg, clasp, type, parent, allocKind, newKind));
+    RootedObject obj(cxArg, NewObject(cxArg, type, parent, allocKind, newKind));
     if (!obj)
         return nullptr;
 
@@ -1428,7 +1430,7 @@ js::NewObjectWithClassProtoCommon(ExclusiveContext *cxArg,
     if (!type)
         return nullptr;
 
-    JSObject *obj = NewObject(cxArg, clasp, type, parent, allocKind, newKind);
+    JSObject *obj = NewObject(cxArg, type, parent, allocKind, newKind);
     if (!obj)
         return nullptr;
 
@@ -1462,19 +1464,19 @@ js::NewObjectWithType(JSContext *cx, HandleTypeObject type, JSObject *parent, gc
         newKind == GenericObject &&
         !cx->compartment()->hasObjectMetadataCallback())
     {
-        if (cache.lookupType(type->clasp(), type, allocKind, &entry)) {
+        if (cache.lookupType(type, allocKind, &entry)) {
             JSObject *obj = cache.newObjectFromHit(cx, entry, GetInitialHeap(newKind, type->clasp()));
             if (obj)
                 return obj;
         }
     }
 
-    JSObject *obj = NewObject(cx, type->clasp(), type, parent, allocKind, newKind);
+    JSObject *obj = NewObject(cx, type, parent, allocKind, newKind);
     if (!obj)
         return nullptr;
 
     if (entry != -1 && !obj->hasDynamicSlots())
-        cache.fillType(entry, type->clasp(), type, allocKind, obj);
+        cache.fillType(entry, type, allocKind, obj);
 
     return obj;
 }
diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index d7bf5ffd137a..22267979426c 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -340,10 +340,8 @@ class NewObjectCache
     inline bool lookupGlobal(const Class *clasp, js::GlobalObject *global, gc::AllocKind kind,
                              EntryIndex *pentry);
 
-    bool lookupType(const Class *clasp, js::types::TypeObject *type, gc::AllocKind kind,
-                    EntryIndex *pentry)
-    {
-        return lookup(clasp, type, kind, pentry);
+    bool lookupType(js::types::TypeObject *type, gc::AllocKind kind, EntryIndex *pentry) {
+        return lookup(type->clasp(), type, kind, pentry);
     }
 
     /*
@@ -359,11 +357,11 @@ class NewObjectCache
     inline void fillGlobal(EntryIndex entry, const Class *clasp, js::GlobalObject *global,
                            gc::AllocKind kind, JSObject *obj);
 
-    void fillType(EntryIndex entry, const Class *clasp, js::types::TypeObject *type, gc::AllocKind kind,
+    void fillType(EntryIndex entry, js::types::TypeObject *type, gc::AllocKind kind,
                   JSObject *obj)
     {
         JS_ASSERT(obj->type() == type);
-        return fill(entry, clasp, type, kind, obj);
+        return fill(entry, type->clasp(), type, kind, obj);
     }
 
     /* Invalidate any entries which might produce an object with shape/proto. */
diff --git a/js/src/vm/Shape.cpp b/js/src/vm/Shape.cpp
index 840bafdac07e..0b313cffaebe 100644
--- a/js/src/vm/Shape.cpp
+++ b/js/src/vm/Shape.cpp
@@ -1658,7 +1658,7 @@ NewObjectCache::invalidateEntriesForShape(JSContext *cx, HandleShape shape, Hand
         PodZero(&entries[entry]);
     if (!proto->is<GlobalObject>() && lookupProto(clasp, proto, kind, &entry))
         PodZero(&entries[entry]);
-    if (lookupType(clasp, type, kind, &entry))
+    if (lookupType(type, kind, &entry))
         PodZero(&entries[entry]);
 }