diff --git a/components/msg/constellation_msg.rs b/components/msg/constellation_msg.rs
index 26a4eb77642..46697ad7645 100644
--- a/components/msg/constellation_msg.rs
+++ b/components/msg/constellation_msg.rs
@@ -224,17 +224,21 @@ impl PipelineNamespace {
 
 thread_local!(pub static PIPELINE_NAMESPACE: Cell<Option<PipelineNamespace>> = Cell::new(None));
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
+#[derive(
+    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
+)]
 pub struct PipelineNamespaceId(pub u32);
 
 #[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
 pub struct PipelineIndex(pub NonZeroU32);
 malloc_size_of_is_0!(PipelineIndex);
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
+#[derive(
+    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
+)]
 pub struct PipelineId {
     pub namespace_id: PipelineNamespaceId,
-    pub index: PipelineIndex
+    pub index: PipelineIndex,
 }
 
 impl PipelineId {
@@ -289,7 +293,9 @@ impl fmt::Display for PipelineId {
 pub struct BrowsingContextIndex(pub NonZeroU32);
 malloc_size_of_is_0!(BrowsingContextIndex);
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
+#[derive(
+    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
+)]
 pub struct BrowsingContextId {
     pub namespace_id: PipelineNamespaceId,
     pub index: BrowsingContextIndex,
@@ -316,7 +322,9 @@ impl fmt::Display for BrowsingContextId {
 
 thread_local!(pub static TOP_LEVEL_BROWSING_CONTEXT_ID: Cell<Option<TopLevelBrowsingContextId>> = Cell::new(None));
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
+#[derive(
+    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
+)]
 pub struct TopLevelBrowsingContextId(BrowsingContextId);
 
 impl TopLevelBrowsingContextId {
@@ -362,7 +370,9 @@ impl PartialEq<BrowsingContextId> for TopLevelBrowsingContextId {
 pub struct HistoryStateIndex(pub NonZeroU32);
 malloc_size_of_is_0!(HistoryStateIndex);
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
+#[derive(
+    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
+)]
 pub struct HistoryStateId {
     pub namespace_id: PipelineNamespaceId,
     pub index: HistoryStateIndex,
@@ -390,13 +400,19 @@ impl fmt::Display for HistoryStateId {
 // We provide ids just for unit testing.
 pub const TEST_NAMESPACE: PipelineNamespaceId = PipelineNamespaceId(1234);
 #[allow(unsafe_code)]
-pub const TEST_PIPELINE_INDEX: PipelineIndex = unsafe { PipelineIndex(NonZeroU32::new_unchecked(5678)) };
-pub const TEST_PIPELINE_ID: PipelineId = PipelineId { namespace_id: TEST_NAMESPACE, index: TEST_PIPELINE_INDEX };
+pub const TEST_PIPELINE_INDEX: PipelineIndex =
+    unsafe { PipelineIndex(NonZeroU32::new_unchecked(5678)) };
+pub const TEST_PIPELINE_ID: PipelineId = PipelineId {
+    namespace_id: TEST_NAMESPACE,
+    index: TEST_PIPELINE_INDEX,
+};
 #[allow(unsafe_code)]
 pub const TEST_BROWSING_CONTEXT_INDEX: BrowsingContextIndex =
     unsafe { BrowsingContextIndex(NonZeroU32::new_unchecked(8765)) };
-pub const TEST_BROWSING_CONTEXT_ID: BrowsingContextId =
-    BrowsingContextId { namespace_id: TEST_NAMESPACE, index: TEST_BROWSING_CONTEXT_INDEX };
+pub const TEST_BROWSING_CONTEXT_ID: BrowsingContextId = BrowsingContextId {
+    namespace_id: TEST_NAMESPACE,
+    index: TEST_BROWSING_CONTEXT_INDEX,
+};
 
 // Used to specify the kind of input method editor appropriate to edit a field.
 // This is a subset of htmlinputelement::InputType because some variants of InputType
diff --git a/components/msg/lib.rs b/components/msg/lib.rs
index f7dc97a82a1..ec9619bab05 100644
--- a/components/msg/lib.rs
+++ b/components/msg/lib.rs
@@ -6,9 +6,12 @@
 
 #[macro_use]
 extern crate bitflags;
-#[macro_use] extern crate malloc_size_of;
-#[macro_use] extern crate malloc_size_of_derive;
-#[macro_use] extern crate serde;
+#[macro_use]
+extern crate malloc_size_of;
+#[macro_use]
+extern crate malloc_size_of_derive;
+#[macro_use]
+extern crate serde;
 extern crate webrender_api;
 
 pub mod constellation_msg;
diff --git a/components/msg/tests/size_of.rs b/components/msg/tests/size_of.rs
index 54e5294c7d5..62e2647ea61 100644
--- a/components/msg/tests/size_of.rs
+++ b/components/msg/tests/size_of.rs
@@ -5,7 +5,8 @@
 #![cfg(target_pointer_width = "64")]
 
 extern crate msg;
-#[macro_use] extern crate size_of_test;
+#[macro_use]
+extern crate size_of_test;
 
 use msg::constellation_msg::BrowsingContextId;
 use msg::constellation_msg::PipelineId;
@@ -14,6 +15,18 @@ use msg::constellation_msg::TopLevelBrowsingContextId;
 size_of_test!(test_size_of_pipeline_id, PipelineId, 8);
 size_of_test!(test_size_of_optional_pipeline_id, Option<PipelineId>, 8);
 size_of_test!(test_size_of_browsing_context_id, BrowsingContextId, 8);
-size_of_test!(test_size_of_optional_browsing_context_id, Option<BrowsingContextId>, 8);
-size_of_test!(test_size_of_top_level_browsing_context_id, TopLevelBrowsingContextId, 8);
-size_of_test!(test_size_of_top_level_optional_browsing_context_id, Option<TopLevelBrowsingContextId>, 8);
+size_of_test!(
+    test_size_of_optional_browsing_context_id,
+    Option<BrowsingContextId>,
+    8
+);
+size_of_test!(
+    test_size_of_top_level_browsing_context_id,
+    TopLevelBrowsingContextId,
+    8
+);
+size_of_test!(
+    test_size_of_top_level_optional_browsing_context_id,
+    Option<TopLevelBrowsingContextId>,
+    8
+);