diff --git a/glue.rs b/glue.rs
index cef0fa829..4c7a0c23d 100644
--- a/glue.rs
+++ b/glue.rs
@@ -44,9 +44,10 @@ pub struct ProxyTraps {
     //regexp_toShared: *u8,
     defaultValue: *u8,
     iteratorNext: *u8,
-    finalize: *u8,
+    finalize: extern "C" fn(*JSFreeOp, *JSObject),
     getElementIfPresent: *u8,
-    getPrototypeOf: *u8
+    getPrototypeOf: *u8,
+    trace: Option<extern "C" fn(*mut JSTracer, *JSObject)>
 }
 
 #[link_args="-ljsglue"]
diff --git a/jsglue.cpp b/jsglue.cpp
index dbc45abf4..6b31aa13a 100644
--- a/jsglue.cpp
+++ b/jsglue.cpp
@@ -59,6 +59,7 @@ struct ProxyTraps {
     bool (*getElementIfPresent)(JSContext *cx, JSObject *obj, JSObject *receiver,
                                 uint32_t index, JS::Value *vp, bool *present);
     bool (*getPrototypeOf)(JSContext *cx, JSObject *proxy, JSObject **proto);
+    void (*trace)(JSTracer *trc, JSObject *proxy);
 };
 
 int HandlerFamily = js::JSSLOT_PROXY_EXTRA + 0 /*JSPROXYSLOT_EXPANDO*/;
@@ -256,6 +257,13 @@ class ForwardingProxyHandler : public js::BaseProxyHandler
                 mTraps.getPrototypeOf(cx, proxy, proto) :
                 BaseProxyHandler::getPrototypeOf(cx, proxy, proto);
     }
+
+    virtual void trace(JSTracer *trc, JSObject *proxy)
+    {
+        return mTraps.trace ?
+                mTraps.trace(trc, proxy) :
+                BaseProxyHandler::trace(trc, proxy);
+    }
 };
 
 extern "C" {