diff --git a/components/net/image_cache_thread.rs b/components/net/image_cache_thread.rs
index 2ead7e06db6..a9cdca099d7 100644
--- a/components/net/image_cache_thread.rs
+++ b/components/net/image_cache_thread.rs
@@ -336,6 +336,21 @@ fn get_placeholder_image(webrender_api: &webrender_traits::RenderApi) -> io::Res
     Ok(Arc::new(image))
 }
 
+fn premultiply(data: &mut [u8]) {
+    let length = data.len();
+
+    for i in (0..length).step_by(4) {
+        let b = data[i + 0] as u32;
+        let g = data[i + 1] as u32;
+        let r = data[i + 2] as u32;
+        let a = data[i + 3] as u32;
+
+        data[i + 0] = (b * a / 255) as u8;
+        data[i + 1] = (g * a / 255) as u8;
+        data[i + 2] = (r * a / 255) as u8;
+    }
+}
+
 impl ImageCache {
     fn run(webrender_api: webrender_traits::RenderApi,
            ipc_command_receiver: IpcReceiver<ImageCacheCommand>) {
@@ -484,6 +499,9 @@ impl ImageCache {
                 let format = convert_format(image.format);
                 let mut bytes = Vec::new();
                 bytes.extend_from_slice(&*image.bytes);
+                if format == webrender_traits::ImageFormat::RGBA8 {
+                    premultiply(bytes.as_mut_slice());
+                }
                 let descriptor = webrender_traits::ImageDescriptor {
                     width: image.width,
                     height: image.height,
diff --git a/components/net/lib.rs b/components/net/lib.rs
index b2a1ff97764..90999cfcf62 100644
--- a/components/net/lib.rs
+++ b/components/net/lib.rs
@@ -5,6 +5,7 @@
 #![deny(unsafe_code)]
 #![feature(box_syntax)]
 #![feature(mpsc_select)]
+#![feature(step_by)]
 
 extern crate brotli;
 extern crate cookie as cookie_rs;
diff --git a/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_mipmap.html b/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_mipmap.html
index 5391417795d..09ca0fba7ee 100644
--- a/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_mipmap.html
+++ b/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_mipmap.html
@@ -106,6 +106,7 @@
 
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
+      gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
       gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
       gl.generateMipmap(gl.TEXTURE_2D);
 
diff --git a/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_simple.html b/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_simple.html
index f3bba7d4f2d..3defd7a5f96 100644
--- a/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_simple.html
+++ b/tests/wpt/mozilla/tests/mozilla/webgl/tex_image_2d_simple.html
@@ -106,6 +106,7 @@
 
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
+      gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
       gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
 
       gl.drawArrays(gl.TRIANGLES, 0, 6);