--- a/servo/components/style/gecko/restyle_damage.rs
+++ b/servo/components/style/gecko/restyle_damage.rs
@@ -50,17 +50,17 @@ impl GeckoRestyleDamage {
         source: &nsStyleContext,
         new_style: &Arc<ComputedValues>
     ) -> StyleDifference {
         // TODO(emilio): Const-ify this?
         let context = source as *const nsStyleContext as *mut nsStyleContext;
         let mut any_style_changed: bool = false;
         let hint = unsafe {
             bindings::Gecko_CalcStyleDifference(context,
-                                                &new_style,
+                                                new_style.as_style_context(),
                                                 &mut any_style_changed)
         };
         let change = if any_style_changed { StyleChange::Changed } else { StyleChange::Unchanged };
         StyleDifference::new(GeckoRestyleDamage(hint), change)
     }
 
     /// Returns true if this restyle damage contains all the damage of |other|.
     pub fn contains(self, other: Self) -> bool {

--- a/servo/components/style/properties/gecko.mako.rs
+++ b/servo/components/style/properties/gecko.mako.rs
@@ -132,16 +132,20 @@ impl ComputedValues {
         let atom = (self.0)._base.mPseudoTag.raw::<structs::nsIAtom>();
         if atom.is_null() {
             return None;
         }
 
         let atom = Atom::from(atom);
         PseudoElement::from_atom(&atom)
     }
+
+    pub fn as_style_context(&self) -> &::gecko_bindings::structs::mozilla::ServoStyleContext {
+        &self.0
+    }
 }
 
 impl Drop for ComputedValues {
     fn drop(&mut self) {
         unsafe {
             bindings::Gecko_ServoStyleContext_Destroy(&mut self.0);
         }
     }