--- a/js/src/builtin/TypedObject.cpp
+++ b/js/src/builtin/TypedObject.cpp
@@ -817,18 +817,17 @@ js::IsTypedObjectArray(JSObject &obj)
 }
 
 /*********************************
  * StructType class
  */
 
 const Class StructTypeDescr::class_ = {
     "StructType",
-    JSCLASS_HAS_RESERVED_SLOTS(JS_DESCR_SLOTS) |
-    JSCLASS_HAS_PRIVATE, // used to store FieldList
+    JSCLASS_HAS_RESERVED_SLOTS(JS_DESCR_SLOTS),
     JS_PropertyStub,
     JS_DeletePropertyStub,
     JS_PropertyStub,
     JS_StrictPropertyStub,
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     nullptr, /* finalize */