diff --git a/components/layout/block.rs b/components/layout/block.rs
index 231f406d25a..abaa80a06ab 100644
--- a/components/layout/block.rs
+++ b/components/layout/block.rs
@@ -1869,11 +1869,11 @@ impl Flow for BlockFlow {
         self.fragment.border_box - self.fragment.style().logical_border_width()
     }
 
-    fn layer_id(&self, fragment_index: uint) -> LayerId {
+    fn layer_id(&self, fragment_index: u32) -> LayerId {
         // FIXME(#2010, pcwalton): This is a hack and is totally bogus in the presence of pseudo-
         // elements. But until we have incremental reflow we can't do better--we recreate the flow
         // for every DOM node so otherwise we nuke layers on every reflow.
-        LayerId(self.fragment.node.id() as uint, fragment_index)
+        LayerId(self.fragment.node.id() as usize, fragment_index)
     }
 
     fn is_absolute_containing_block(&self) -> bool {
diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index 46b69e2deaa..2840f071411 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -311,12 +311,9 @@ pub trait Flow: fmt::Debug + Sync {
 
     /// Returns a layer ID for the given fragment.
     #[allow(unsafe_code)]
-    fn layer_id(&self, fragment_id: uint) -> LayerId {
-        unsafe {
-            let obj = mem::transmute::<&&Self, &raw::TraitObject>(&self);
-            let pointer: uint = mem::transmute(obj.data);
-            LayerId(pointer, fragment_id)
-        }
+    fn layer_id(&self, fragment_id: u32) -> LayerId {
+        let obj = unsafe { mem::transmute::<&&Self, &raw::TraitObject>(&self) };
+        LayerId(obj.data as usize, fragment_id)
     }
 
     /// Attempts to perform incremental fixup of this flow by replacing its fragment's style with
diff --git a/components/msg/compositor_msg.rs b/components/msg/compositor_msg.rs
index c51a0df6a0c..d306af649a9 100644
--- a/components/msg/compositor_msg.rs
+++ b/components/msg/compositor_msg.rs
@@ -44,7 +44,7 @@ impl Epoch {
 }
 
 #[derive(Clone, PartialEq, Eq, Copy)]
-pub struct LayerId(pub uint, pub uint);
+pub struct LayerId(pub usize, pub u32);
 
 impl Debug for LayerId {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {