diff --git a/components/canvas/Cargo.toml b/components/canvas/Cargo.toml
index 11a0580c34e..64f258e5bbe 100644
--- a/components/canvas/Cargo.toml
+++ b/components/canvas/Cargo.toml
@@ -12,10 +12,6 @@ path = "lib.rs"
 git = "https://github.com/servo/rust-azure"
 features = ["plugins"]
 
-[dependencies.layers]
-git = "https://github.com/servo/rust-layers"
-features = ["plugins"]
-
 [dependencies.canvas_traits]
 path = "../canvas_traits"
 
diff --git a/components/canvas/lib.rs b/components/canvas/lib.rs
index 1aee40b1e14..027036db74c 100644
--- a/components/canvas/lib.rs
+++ b/components/canvas/lib.rs
@@ -14,7 +14,6 @@ extern crate euclid;
 extern crate gfx_traits;
 extern crate gleam;
 extern crate ipc_channel;
-extern crate layers;
 #[macro_use]
 extern crate log;
 extern crate num_traits;
diff --git a/components/canvas_traits/Cargo.toml b/components/canvas_traits/Cargo.toml
index 04a651ea43b..7586b2d29f4 100644
--- a/components/canvas_traits/Cargo.toml
+++ b/components/canvas_traits/Cargo.toml
@@ -25,9 +25,6 @@ features = [ "nightly" ]
 [dependencies.plugins]
 path = "../plugins"
 
-[dependencies.util]
-path = "../util"
-
 [dependencies.webrender_traits]
 git = "https://github.com/servo/webrender_traits"
 
@@ -36,6 +33,5 @@ cssparser = {version = "0.5.4", features = ["heap_size", "serde-serialization"]}
 euclid = {version = "0.6.4", features = ["plugins"]}
 heapsize = "0.3.0"
 heapsize_plugin = "0.1.2"
-offscreen_gl_context = "0.1.2"
 serde_macros = "0.7"
 
diff --git a/components/canvas_traits/lib.rs b/components/canvas_traits/lib.rs
index fe1dbf24e17..8bf7fa0fba9 100644
--- a/components/canvas_traits/lib.rs
+++ b/components/canvas_traits/lib.rs
@@ -17,9 +17,7 @@ extern crate euclid;
 extern crate gfx_traits;
 extern crate heapsize;
 extern crate ipc_channel;
-extern crate offscreen_gl_context;
 extern crate serde;
-extern crate util;
 extern crate webrender_traits;
 
 use azure::azure::{AzColor, AzFloat};
diff --git a/components/devtools/Cargo.toml b/components/devtools/Cargo.toml
index 095f73655ed..da2f1c193ca 100644
--- a/components/devtools/Cargo.toml
+++ b/components/devtools/Cargo.toml
@@ -25,7 +25,6 @@ git = "https://github.com/servo/ipc-channel"
 
 [dependencies]
 hyper = { version = "0.8", features = [ "serde-serialization" ] }
-log = "0.3.5"
 serde = "0.7"
 serde_json = "0.7"
 serde_macros = "0.7"
diff --git a/components/devtools/lib.rs b/components/devtools/lib.rs
index e9fe79ef14a..72a6d9ba192 100644
--- a/components/devtools/lib.rs
+++ b/components/devtools/lib.rs
@@ -23,8 +23,6 @@
 extern crate devtools_traits;
 extern crate hyper;
 extern crate ipc_channel;
-#[macro_use]
-extern crate log;
 extern crate msg;
 extern crate serde;
 extern crate serde_json;
diff --git a/components/devtools_traits/Cargo.toml b/components/devtools_traits/Cargo.toml
index fb9fb4f2cf5..78f9784b15d 100644
--- a/components/devtools_traits/Cargo.toml
+++ b/components/devtools_traits/Cargo.toml
@@ -11,9 +11,6 @@ path = "lib.rs"
 [dependencies.msg]
 path = "../msg"
 
-[dependencies.util]
-path = "../util"
-
 [dependencies.ipc-channel]
 git = "https://github.com/servo/ipc-channel"
 
diff --git a/components/devtools_traits/lib.rs b/components/devtools_traits/lib.rs
index f084d70d638..9a46ddc0000 100644
--- a/components/devtools_traits/lib.rs
+++ b/components/devtools_traits/lib.rs
@@ -15,6 +15,7 @@
 #![feature(custom_derive, plugin)]
 #![plugin(heapsize_plugin, serde_macros)]
 
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 extern crate heapsize;
@@ -24,7 +25,6 @@ extern crate msg;
 extern crate serde;
 extern crate time;
 extern crate url;
-extern crate util;
 
 use hyper::header::Headers;
 use hyper::http::RawStatus;
diff --git a/components/gfx/lib.rs b/components/gfx/lib.rs
index f60575cd625..1eecec8e321 100644
--- a/components/gfx/lib.rs
+++ b/components/gfx/lib.rs
@@ -23,6 +23,7 @@
 extern crate alloc;
 extern crate app_units;
 extern crate azure;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 
@@ -49,6 +50,7 @@ extern crate harfbuzz_sys as harfbuzz;
 extern crate heapsize;
 extern crate ipc_channel;
 extern crate layers;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate lazy_static;
 extern crate libc;
diff --git a/components/gfx_traits/Cargo.toml b/components/gfx_traits/Cargo.toml
index d341ac03823..c6a99dbe218 100644
--- a/components/gfx_traits/Cargo.toml
+++ b/components/gfx_traits/Cargo.toml
@@ -22,9 +22,6 @@ path = "../msg"
 [dependencies.plugins]
 path = "../plugins"
 
-[dependencies.util]
-path = "../util"
-
 [dependencies]
 euclid = {version = "0.6.5", features = ["plugins"]}
 heapsize = "0.3.0"
diff --git a/components/gfx_traits/lib.rs b/components/gfx_traits/lib.rs
index 0d13f45f4a3..64474d496bf 100644
--- a/components/gfx_traits/lib.rs
+++ b/components/gfx_traits/lib.rs
@@ -16,7 +16,6 @@ extern crate heapsize;
 extern crate layers;
 extern crate msg;
 extern crate serde;
-extern crate util;
 
 pub mod color;
 mod paint_listener;
diff --git a/components/layout/Cargo.toml b/components/layout/Cargo.toml
index 35ca6cd1173..f3a91e4f916 100644
--- a/components/layout/Cargo.toml
+++ b/components/layout/Cargo.toml
@@ -72,7 +72,6 @@ libc = "0.2"
 log = "0.3.5"
 rustc-serialize = "0.3"
 selectors = {version = "0.5.1", features = ["heap_size"]}
-serde = "0.7"
 serde_json = "0.7"
 serde_macros = "0.7"
 smallvec = "0.1"
diff --git a/components/layout/lib.rs b/components/layout/lib.rs
index 4f1d9abdac1..f4978023d76 100644
--- a/components/layout/lib.rs
+++ b/components/layout/lib.rs
@@ -21,6 +21,7 @@
 
 extern crate app_units;
 extern crate azure;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 extern crate canvas_traits;
@@ -49,7 +50,6 @@ extern crate rustc_serialize;
 extern crate script;
 extern crate script_traits;
 extern crate selectors;
-extern crate serde;
 extern crate serde_json;
 extern crate smallvec;
 #[macro_use(atom, ns)] extern crate string_cache;
diff --git a/components/msg/lib.rs b/components/msg/lib.rs
index 0f2a16228a1..bd97c3a33da 100644
--- a/components/msg/lib.rs
+++ b/components/msg/lib.rs
@@ -7,6 +7,7 @@
 
 #![deny(unsafe_code)]
 
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 extern crate euclid;
diff --git a/components/net_traits/lib.rs b/components/net_traits/lib.rs
index 6d4bc855d19..407b0dd50fb 100644
--- a/components/net_traits/lib.rs
+++ b/components/net_traits/lib.rs
@@ -17,6 +17,7 @@ extern crate heapsize;
 extern crate hyper;
 extern crate image as piston_image;
 extern crate ipc_channel;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate lazy_static;
 #[macro_use]
diff --git a/components/profile/lib.rs b/components/profile/lib.rs
index 53b7fa0ae2b..5885d85588d 100644
--- a/components/profile/lib.rs
+++ b/components/profile/lib.rs
@@ -10,6 +10,7 @@
 
 #![deny(unsafe_code)]
 
+#[allow(unused_extern_crates)]
 #[cfg(not(target_os = "windows"))]
 extern crate alloc_jemalloc;
 extern crate hbs_pow;
diff --git a/components/script/lib.rs b/components/script/lib.rs
index 2827238dcef..0748ae954a6 100644
--- a/components/script/lib.rs
+++ b/components/script/lib.rs
@@ -30,6 +30,7 @@
 
 extern crate angle;
 extern crate app_units;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 extern crate canvas;
diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 699fb329559..9acf75b6e97 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -30,7 +30,6 @@ dependencies = [
  "net_tests 0.0.1",
  "net_traits 0.0.1",
  "net_traits_tests 0.0.1",
- "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugin_compiletest 0.0.1",
  "profile 0.0.1",
  "profile_tests 0.0.1",
@@ -168,7 +167,6 @@ dependencies = [
  "gfx_traits 0.0.1",
  "gleam 0.2.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "layers 0.2.4 (git+https://github.com/servo/rust-layers)",
  "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.1.32 (registry+https://github.com/rust-lang/crates.io-index)",
  "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -188,11 +186,9 @@ dependencies = [
  "heapsize 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "heapsize_plugin 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
  "webrender_traits 0.1.0 (git+https://github.com/servo/webrender_traits)",
 ]
 
@@ -409,7 +405,6 @@ dependencies = [
  "devtools_traits 0.0.1",
  "hyper 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -434,7 +429,6 @@ dependencies = [
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
 ]
 
 [[package]]
@@ -737,7 +731,6 @@ dependencies = [
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
 ]
 
 [[package]]
@@ -1063,7 +1056,6 @@ dependencies = [
  "script 0.0.1",
  "script_traits 0.0.1",
  "selectors 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/components/servo/Cargo.toml b/components/servo/Cargo.toml
index 10e4573bb7c..b41979e41ac 100644
--- a/components/servo/Cargo.toml
+++ b/components/servo/Cargo.toml
@@ -130,7 +130,7 @@ optional = true
 version = "0.1.3"
 optional = true
 
-[dependencies.log]
+[target.arm-linux-androideabi.dependencies.log]
 version = "0.3"
 features = ["release_max_level_info"]
 
@@ -171,5 +171,4 @@ bitflags = "0.3"
 env_logger = "0.3"
 euclid = {version = "0.6.4", features = ["plugins"]}
 libc = "0.2"
-offscreen_gl_context = "0.1.2"
 url = {version = "0.5.7", features = ["heap_size", "serde_serialization", "query_encoding"]}
diff --git a/components/servo/main.rs b/components/servo/main.rs
index b5e2812a595..214d9ee101d 100644
--- a/components/servo/main.rs
+++ b/components/servo/main.rs
@@ -21,14 +21,13 @@
 #[macro_use]
 extern crate android_glue;
 extern crate env_logger;
-extern crate gleam;
 // The window backed by glutin
 extern crate glutin_app as app;
 #[cfg(target_os = "android")]
 extern crate libc;
+#[cfg(target_os = "android")]
 #[macro_use]
 extern crate log;
-extern crate offscreen_gl_context;
 // The Servo engine
 extern crate servo;
 
diff --git a/components/style/lib.rs b/components/style/lib.rs
index 86e24be674d..00d5d079066 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -19,6 +19,7 @@
 #![recursion_limit = "500"]  // For match_ignore_ascii_case in PropertyDeclaration::parse
 
 extern crate app_units;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 extern crate core;
@@ -28,10 +29,12 @@ extern crate encoding;
 extern crate euclid;
 extern crate fnv;
 extern crate heapsize;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate lazy_static;
 #[macro_use]
 extern crate log;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate matches;
 extern crate num_traits;
diff --git a/components/util/lib.rs b/components/util/lib.rs
index 5eb530f1b19..b4998b0580c 100644
--- a/components/util/lib.rs
+++ b/components/util/lib.rs
@@ -18,6 +18,7 @@
 #![deny(unsafe_code)]
 
 extern crate app_units;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate bitflags;
 extern crate deque;
@@ -27,6 +28,7 @@ extern crate heapsize;
 extern crate ipc_channel;
 #[cfg(feature = "non-geckolib")]
 extern crate js;
+#[allow(unused_extern_crates)]
 #[macro_use]
 extern crate lazy_static;
 extern crate libc;
diff --git a/components/util/resource_files.rs b/components/util/resource_files.rs
index 06e8a428361..58d6a17441c 100644
--- a/components/util/resource_files.rs
+++ b/components/util/resource_files.rs
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#[cfg(not(target_os = "android"))]
 use std::env;
 use std::fs::File;
 use std::io::{self, Read};
diff --git a/components/webdriver_server/lib.rs b/components/webdriver_server/lib.rs
index 03ea0291caf..25275c1bc13 100644
--- a/components/webdriver_server/lib.rs
+++ b/components/webdriver_server/lib.rs
@@ -14,8 +14,6 @@ extern crate compositing;
 extern crate hyper;
 extern crate image;
 extern crate ipc_channel;
-#[macro_use]
-extern crate log;
 extern crate msg;
 extern crate regex;
 extern crate rustc_serialize;
diff --git a/ports/cef/Cargo.lock b/ports/cef/Cargo.lock
index 39a720034b5..01008dc1505 100644
--- a/ports/cef/Cargo.lock
+++ b/ports/cef/Cargo.lock
@@ -152,7 +152,6 @@ dependencies = [
  "gfx_traits 0.0.1",
  "gleam 0.2.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "layers 0.2.4 (git+https://github.com/servo/rust-layers)",
  "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.1.32 (registry+https://github.com/rust-lang/crates.io-index)",
  "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -172,11 +171,9 @@ dependencies = [
  "heapsize 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "heapsize_plugin 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
  "webrender_traits 0.1.0 (git+https://github.com/servo/webrender_traits)",
 ]
 
@@ -378,7 +375,6 @@ dependencies = [
  "devtools_traits 0.0.1",
  "hyper 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -403,7 +399,6 @@ dependencies = [
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
 ]
 
 [[package]]
@@ -656,7 +651,6 @@ dependencies = [
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
 ]
 
 [[package]]
@@ -982,7 +976,6 @@ dependencies = [
  "script 0.0.1",
  "script_traits 0.0.1",
  "selectors 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1781,7 +1774,6 @@ dependencies = [
  "msg 0.0.1",
  "net 0.0.1",
  "net_traits 0.0.1",
- "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "profile 0.0.1",
  "profile_traits 0.0.1",
  "script 0.0.1",
diff --git a/ports/glutin/lib.rs b/ports/glutin/lib.rs
index d8c6a41ce5b..367ae7bc71b 100644
--- a/ports/glutin/lib.rs
+++ b/ports/glutin/lib.rs
@@ -9,6 +9,7 @@
 #[macro_use] extern crate bitflags;
 #[cfg(target_os = "macos")] extern crate cgl;
 extern crate compositing;
+#[allow(unused_extern_crates)]
 #[cfg(target_os = "android")] extern crate egl;
 extern crate euclid;
 extern crate gleam;
diff --git a/ports/glutin/window.rs b/ports/glutin/window.rs
index e691191f3dd..1a130a43d2c 100644
--- a/ports/glutin/window.rs
+++ b/ports/glutin/window.rs
@@ -22,13 +22,16 @@ use msg::constellation_msg::{self, Key};
 use net_traits::net_error_list::NetError;
 use script_traits::{TouchEventType, TouchpadPressurePhase};
 use std::cell::{Cell, RefCell};
+#[cfg(not(target_os = "android"))]
 use std::os::raw::c_void;
 use std::rc::Rc;
 use std::sync::mpsc::{channel, Sender};
 use style_traits::cursor::Cursor;
 use url::Url;
 use util::geometry::ScreenPx;
-use util::opts::{self, RenderApi};
+use util::opts;
+#[cfg(not(target_os = "android"))]
+use util::opts::RenderApi;
 
 static mut g_nested_event_loop_listener: Option<*mut (NestedEventLoopListener + 'static)> = None;
 
diff --git a/ports/gonk/Cargo.lock b/ports/gonk/Cargo.lock
index c2f7dcb6978..01e421d6765 100644
--- a/ports/gonk/Cargo.lock
+++ b/ports/gonk/Cargo.lock
@@ -145,7 +145,6 @@ dependencies = [
  "gfx_traits 0.0.1",
  "gleam 0.2.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "layers 0.2.4 (git+https://github.com/servo/rust-layers)",
  "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.1.32 (registry+https://github.com/rust-lang/crates.io-index)",
  "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -165,11 +164,9 @@ dependencies = [
  "heapsize 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "heapsize_plugin 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
  "webrender_traits 0.1.0 (git+https://github.com/servo/webrender_traits)",
 ]
 
@@ -371,7 +368,6 @@ dependencies = [
  "devtools_traits 0.0.1",
  "hyper 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
- "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -396,7 +392,6 @@ dependencies = [
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
 ]
 
 [[package]]
@@ -659,7 +654,6 @@ dependencies = [
  "plugins 0.0.1",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
 ]
 
 [[package]]
@@ -964,7 +958,6 @@ dependencies = [
  "script 0.0.1",
  "script_traits 0.0.1",
  "selectors 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1762,7 +1755,6 @@ dependencies = [
  "msg 0.0.1",
  "net 0.0.1",
  "net_traits 0.0.1",
- "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "profile 0.0.1",
  "profile_traits 0.0.1",
  "script 0.0.1",
diff --git a/python/servo/build_commands.py b/python/servo/build_commands.py
index 00aae38cf78..31d8d1ded39 100644
--- a/python/servo/build_commands.py
+++ b/python/servo/build_commands.py
@@ -230,6 +230,8 @@ class MachCommands(CommandBase):
         if not (self.config["build"]["ccache"] == ""):
             env['CCACHE'] = self.config["build"]["ccache"]
 
+        env['RUSTFLAGS'] = env.get('RUSTFLAGS', "") + " -W unused-extern-crates"
+
         status = call(
             ["cargo", "build"] + opts,
             env=env, cwd=self.servo_crate(), verbose=verbose)