diff --git a/components/style/gecko_bindings/sugar/ns_style_coord.rs b/components/style/gecko_bindings/sugar/ns_style_coord.rs
index cf9b684bbb9..abd53037c47 100644
--- a/components/style/gecko_bindings/sugar/ns_style_coord.rs
+++ b/components/style/gecko_bindings/sugar/ns_style_coord.rs
@@ -20,7 +20,7 @@ impl nsStyleCoord {
     }
 }
 
-impl CoordData for nsStyleCoord {
+unsafe impl CoordData for nsStyleCoord {
     #[inline]
     fn unit(&self) -> nsStyleUnit {
         unsafe {
@@ -35,7 +35,7 @@ impl CoordData for nsStyleCoord {
     }
 }
 
-impl CoordDataMut for nsStyleCoord {
+unsafe impl CoordDataMut for nsStyleCoord {
     unsafe fn values_mut(&mut self) -> (&mut nsStyleUnit, &mut nsStyleUnion) {
         let unit = self.get_mUnit_mut() as *mut _;
         let value = self.get_mValue_mut() as *mut _;
@@ -98,7 +98,7 @@ pub struct SidesDataMut<'a> {
     index: usize,
 }
 
-impl<'a> CoordData for SidesData<'a> {
+unsafe impl<'a> CoordData for SidesData<'a> {
     #[inline]
     fn unit(&self) -> nsStyleUnit {
         unsafe {
@@ -112,7 +112,7 @@ impl<'a> CoordData for SidesData<'a> {
         }
     }
 }
-impl<'a> CoordData for SidesDataMut<'a> {
+unsafe impl<'a> CoordData for SidesDataMut<'a> {
     #[inline]
     fn unit(&self) -> nsStyleUnit {
         unsafe {
@@ -126,7 +126,7 @@ impl<'a> CoordData for SidesDataMut<'a> {
         }
     }
 }
-impl<'a> CoordDataMut for SidesDataMut<'a> {
+unsafe impl<'a> CoordDataMut for SidesDataMut<'a> {
     unsafe fn values_mut(&mut self) -> (&mut nsStyleUnit, &mut nsStyleUnion) {
         let unit = &mut self.sides.get_mUnits_mut()[self.index] as *mut _;
         let value = &mut self.sides.get_mValues_mut()[self.index] as *mut _;
@@ -168,7 +168,7 @@ pub struct CornersDataMut<'a> {
     index: usize,
 }
 
-impl<'a> CoordData for CornersData<'a> {
+unsafe impl<'a> CoordData for CornersData<'a> {
     fn unit(&self) -> nsStyleUnit {
         unsafe {
             self.corners.get_mUnits()[self.index]
@@ -180,7 +180,7 @@ impl<'a> CoordData for CornersData<'a> {
         }
     }
 }
-impl<'a> CoordData for CornersDataMut<'a> {
+unsafe impl<'a> CoordData for CornersDataMut<'a> {
     fn unit(&self) -> nsStyleUnit {
         unsafe {
             self.corners.get_mUnits()[self.index]
@@ -192,7 +192,7 @@ impl<'a> CoordData for CornersDataMut<'a> {
         }
     }
 }
-impl<'a> CoordDataMut for CornersDataMut<'a> {
+unsafe impl<'a> CoordDataMut for CornersDataMut<'a> {
     unsafe fn values_mut(&mut self) -> (&mut nsStyleUnit, &mut nsStyleUnion) {
         let unit = &mut self.corners.get_mUnits_mut()[self.index] as *mut _;
         let value = &mut self.corners.get_mValues_mut()[self.index] as *mut _;
@@ -240,7 +240,7 @@ pub enum CoordDataValue {
 
 
 /// A trait to abstract on top of a mutable `nsStyleCoord`-like object.
-pub trait CoordDataMut : CoordData {
+pub unsafe trait CoordDataMut : CoordData {
     /// Get mutably the unit and the union.
     ///
     /// This is unsafe since it's possible to modify the unit without changing
@@ -394,7 +394,7 @@ pub trait CoordDataMut : CoordData {
     }
 }
 /// A trait to abstract on top of a `nsStyleCoord`-like object.
-pub trait CoordData {
+pub unsafe trait CoordData {
     /// Get the unit of this object.
     fn unit(&self) -> nsStyleUnit;
     /// Get the `nsStyleUnion` for this object.