diff --git a/components/compositing/constellation.rs b/components/compositing/constellation.rs
index 86f9e9620a0..1c0e6417df8 100644
--- a/components/compositing/constellation.rs
+++ b/components/compositing/constellation.rs
@@ -1206,26 +1206,24 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
     fn handle_create_canvas_paint_thread_msg(
             &mut self,
             size: &Size2D<i32>,
-            response_sender: IpcSender<(IpcSender<CanvasMsg>, usize)>) {
-        let id = self.canvas_paint_threads.len();
+            response_sender: IpcSender<IpcSender<CanvasMsg>>) {
         let webrender_api = self.webrender_api_sender.clone();
         let (out_of_process_sender, in_process_sender) = CanvasPaintThread::start(*size,
                                                                                   webrender_api);
         self.canvas_paint_threads.push(in_process_sender);
-        response_sender.send((out_of_process_sender, id)).unwrap()
+        response_sender.send(out_of_process_sender).unwrap()
     }
 
     fn handle_create_webgl_paint_thread_msg(
             &mut self,
             size: &Size2D<i32>,
             attributes: GLContextAttributes,
-            response_sender: IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>) {
+            response_sender: IpcSender<Result<IpcSender<CanvasMsg>, String>>) {
         let webrender_api = self.webrender_api_sender.clone();
         let response = match WebGLPaintThread::start(*size, attributes, webrender_api) {
             Ok((out_of_process_sender, in_process_sender)) => {
-                let id = self.webgl_paint_threads.len();
                 self.webgl_paint_threads.push(in_process_sender);
-                Ok((out_of_process_sender, id))
+                Ok(out_of_process_sender)
             },
             Err(msg) => Err(msg),
         };
diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index 566a0ea08b1..aa5c7d9f72b 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -124,7 +124,7 @@ impl CanvasRenderingContext2D {
         let (sender, receiver) = ipc::channel().unwrap();
         let constellation_chan = global.constellation_chan();
         constellation_chan.0.send(ConstellationMsg::CreateCanvasPaintThread(size, sender)).unwrap();
-        let (ipc_renderer, _) = receiver.recv().unwrap();
+        let ipc_renderer = receiver.recv().unwrap();
         CanvasRenderingContext2D {
             reflector_: Reflector::new(),
             ipc_renderer: ipc_renderer,
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index b52894b84c0..5251585ea94 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -94,7 +94,7 @@ impl WebGLRenderingContext {
                           .unwrap();
         let result = receiver.recv().unwrap();
 
-        result.map(|(ipc_renderer, _)| {
+        result.map(|ipc_renderer| {
             WebGLRenderingContext {
                 reflector_: Reflector::new(),
                 ipc_renderer: ipc_renderer,
diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index 73da909cb5f..5b6afa3db1e 100644
--- a/components/script_traits/script_msg.rs
+++ b/components/script_traits/script_msg.rs
@@ -39,12 +39,12 @@ pub enum ScriptMsg {
     ChangeRunningAnimationsState(PipelineId, AnimationState),
     /// Requests that a new 2D canvas thread be created. (This is done in the constellation because
     /// 2D canvases may use the GPU and we don't want to give untrusted content access to the GPU.)
-    CreateCanvasPaintThread(Size2D<i32>, IpcSender<(IpcSender<CanvasMsg>, usize)>),
+    CreateCanvasPaintThread(Size2D<i32>, IpcSender<IpcSender<CanvasMsg>>),
     /// Requests that a new WebGL thread be created. (This is done in the constellation because
     /// WebGL uses the GPU and we don't want to give untrusted content access to the GPU.)
     CreateWebGLPaintThread(Size2D<i32>,
                          GLContextAttributes,
-                         IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>),
+                         IpcSender<Result<IpcSender<CanvasMsg>, String>>),
     /// Dispatched after the DOM load event has fired on a document
     /// Causes a `load` event to be dispatched to any enclosing frame context element
     /// for the given pipeline.