diff --git a/components/canvas/canvas_data.rs b/components/canvas/canvas_data.rs
index db59419f345..dcacddae8b1 100644
--- a/components/canvas/canvas_data.rs
+++ b/components/canvas/canvas_data.rs
@@ -458,11 +458,7 @@ impl<'a> CanvasData<'a> {
         canvas_size: Size2D<f64>,
         chan: IpcSender<ByteBuf>,
     ) {
-        let mut dest_data = self.read_pixels(dest_rect, canvas_size);
-
-        // bgra -> rgba
-        byte_swap(&mut dest_data);
-        chan.send(dest_data.into()).unwrap();
+        chan.send(self.read_pixels(dest_rect, canvas_size).into()).unwrap();
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-context-2d-putimagedata
diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index 67cbceab896..e362fe40a05 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -1115,12 +1115,12 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
         self.send_canvas_2d_msg(Canvas2dMsg::GetImageData(dest_rect, canvas_size, sender));
         let mut data = receiver.recv().unwrap();
 
-        // Un-premultiply alpha
+        // Byte swap and unmultiply alpha.
         for chunk in data.chunks_mut(4) {
-            let alpha = chunk[3] as usize;
-            chunk[0] = UNPREMULTIPLY_TABLE[256 * alpha + chunk[0] as usize];
-            chunk[1] = UNPREMULTIPLY_TABLE[256 * alpha + chunk[1] as usize];
-            chunk[2] = UNPREMULTIPLY_TABLE[256 * alpha + chunk[2] as usize];
+            let (b, g, r, a) = (chunk[0], chunk[1], chunk[2], chunk[3]);
+            chunk[0] = UNPREMULTIPLY_TABLE[256 * (a as usize) + r as usize];
+            chunk[1] = UNPREMULTIPLY_TABLE[256 * (a as usize) + g as usize];
+            chunk[2] = UNPREMULTIPLY_TABLE[256 * (a as usize) + b as usize];
         }
 
         ImageData::new(&self.global(), sw, sh, Some(data.to_vec()))