diff --git a/js/xpconnect/wrappers/XrayWrapper.cpp b/js/xpconnect/wrappers/XrayWrapper.cpp
index 0daf207897f0..6d4d565e059f 100644
--- a/js/xpconnect/wrappers/XrayWrapper.cpp
+++ b/js/xpconnect/wrappers/XrayWrapper.cpp
@@ -201,7 +201,7 @@ XPCWrappedNativeXrayTraits::getWN(JSObject* wrapper)
 }
 
 const JSClass XPCWrappedNativeXrayTraits::HolderClass = {
-    "NativePropertyHolder", JSCLASS_HAS_RESERVED_SLOTS(2)
+    "NativePropertyHolder"
 };