diff --git a/components/style/lib.rs b/components/style/lib.rs
index dae26c5b943..33e6d515994 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -14,6 +14,8 @@
 #![plugin(serde_macros)]
 #![plugin(plugins)]
 
+#![deny(unsafe_code)]
+
 extern crate app_units;
 #[macro_use]
 extern crate bitflags;
@@ -61,6 +63,7 @@ pub mod viewport;
 
 // Generated from the properties.mako.rs template by build.rs
 #[macro_use]
+#[allow(unsafe_code)]
 pub mod properties {
     include!(concat!(env!("OUT_DIR"), "/properties.rs"));
 }
diff --git a/components/style/matching.rs b/components/style/matching.rs
index 3102e9bd733..3e91425cec9 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -197,6 +197,7 @@ impl StyleSharingCandidate {
     /// Attempts to create a style sharing candidate from this node. Returns
     /// the style sharing candidate or `None` if this node is ineligible for
     /// style sharing.
+    #[allow(unsafe_code)]
     fn new<'le, E: TElement<'le>>(element: &E) -> Option<StyleSharingCandidate> {
         let parent_element = match element.parent_element() {
             None => return None,
diff --git a/components/style/selector_matching.rs b/components/style/selector_matching.rs
index dd99a3f26b4..8886797ad42 100644
--- a/components/style/selector_matching.rs
+++ b/components/style/selector_matching.rs
@@ -2,6 +2,9 @@
  * 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/. */
 
+// For lazy_static
+#![allow(unsafe_code)]
+
 use cssparser::{Parser, SourcePosition};
 use dom::TElement;
 use log;
diff --git a/components/style/viewport.rs b/components/style/viewport.rs
index ce67a24a561..e46d22c19b1 100644
--- a/components/style/viewport.rs
+++ b/components/style/viewport.rs
@@ -277,6 +277,7 @@ impl ViewportRule {
         Ok(ViewportRule { declarations: valid_declarations.iter().cascade() })
     }
 
+    #[allow(unsafe_code)]
     pub fn from_meta(content: &str) -> Option<ViewportRule> {
         let mut declarations = HashMap::new();
         macro_rules! push_descriptor {
@@ -458,6 +459,7 @@ impl ViewportDescriptorDeclaration {
     }
 }
 
+#[allow(unsafe_code)]
 fn cascade<'a, I>(iter: I) -> Vec<ViewportDescriptorDeclaration>
     where I: Iterator<Item=&'a ViewportDescriptorDeclaration>
 {