diff --git a/components/devtools_traits/lib.rs b/components/devtools_traits/lib.rs
index f084d70d638..f8498092442 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;
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/layout/lib.rs b/components/layout/lib.rs
index 4f1d9abdac1..558e4a1492d 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;
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 819d0a80335..03e372393de 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 e525a62b70d..deb1e8ba9e5 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/style/lib.rs b/components/style/lib.rs
index 951a32cd3ce..8473572626a 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;
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/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;