diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 6fa16b2c603..5fccae62427 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -177,6 +177,14 @@ unsafe impl<T: JSTraceable + ?Sized> JSTraceable for Box<T> {
     }
 }
 
+unsafe impl<T: JSTraceable> JSTraceable for [T] {
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        for e in self.iter() {
+            e.trace(trc);
+        }
+    }
+}
+
 unsafe impl<T: JSTraceable + Copy> JSTraceable for Cell<T> {
     unsafe fn trace(&self, trc: *mut JSTracer) {
         self.get().trace(trc)
diff --git a/components/script/timers.rs b/components/script/timers.rs
index 54b2d3f2519..f3c09505ff9 100644
--- a/components/script/timers.rs
+++ b/components/script/timers.rs
@@ -350,7 +350,7 @@ pub enum TimerCallback {
 #[derive(JSTraceable, Clone)]
 enum InternalTimerCallback {
     StringTimerCallback(DOMString),
-    FunctionTimerCallback(Rc<Function>, Rc<Vec<Heap<JSVal>>>),
+    FunctionTimerCallback(Rc<Function>, Rc<Box<[Heap<JSVal>]>>),
 }
 
 impl HeapSizeOf for InternalTimerCallback {
@@ -392,7 +392,7 @@ impl JsTimers {
                 for (i, item) in arguments.iter().enumerate() {
                     args.get_mut(i).unwrap().set(item.get());
                 }
-                InternalTimerCallback::FunctionTimerCallback(function, Rc::new(args))
+                InternalTimerCallback::FunctionTimerCallback(function, Rc::new(args.into_boxed_slice()))
             }
         };