diff --git a/components/style/gecko_bindings/bindings.rs b/components/style/gecko_bindings/bindings.rs
index c84ca64587d..b28183c6ab3 100644
--- a/components/style/gecko_bindings/bindings.rs
+++ b/components/style/gecko_bindings/bindings.rs
@@ -1394,7 +1394,7 @@ extern "C" {
     pub fn Servo_StyleSet_FillKeyframesForName(set: RawServoStyleSetBorrowed,
                                                property: *const nsACString,
                                                timing_function:
-                                                   *const nsTimingFunction,
+                                                   nsTimingFunctionBorrowed,
                                                computed_values:
                                                    ServoComputedValuesBorrowed,
                                                keyframe_list:
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index b36d5fc67eb..3216b65acdb 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -48,6 +48,7 @@ use style::gecko_bindings::bindings::RawServoAnimationValueStrong;
 use style::gecko_bindings::bindings::RawServoImportRuleBorrowed;
 use style::gecko_bindings::bindings::ServoComputedValuesBorrowedOrNull;
 use style::gecko_bindings::bindings::nsTArrayBorrowed_uintptr_t;
+use style::gecko_bindings::bindings::nsTimingFunctionBorrowed;
 use style::gecko_bindings::bindings::nsTimingFunctionBorrowedMut;
 use style::gecko_bindings::structs;
 use style::gecko_bindings::structs::{SheetParsingMode, nsIAtom, nsCSSPropertyID};
@@ -57,7 +58,6 @@ use style::gecko_bindings::structs::Loader;
 use style::gecko_bindings::structs::RawGeckoPresContextOwned;
 use style::gecko_bindings::structs::ServoStyleSheet;
 use style::gecko_bindings::structs::nsCSSValueSharedList;
-use style::gecko_bindings::structs::nsTimingFunction;
 use style::gecko_bindings::structs::nsresult;
 use style::gecko_bindings::sugar::ownership::{FFIArcHelpers, HasArcFFI, HasBoxFFI};
 use style::gecko_bindings::sugar::ownership::{HasSimpleFFI, Strong};
@@ -1639,7 +1639,7 @@ pub extern "C" fn Servo_AssertTreeIsClean(root: RawGeckoElementBorrowed) {
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_FillKeyframesForName(raw_data: RawServoStyleSetBorrowed,
                                                       name: *const nsACString,
-                                                      timing_function: *const nsTimingFunction,
+                                                      timing_function: nsTimingFunctionBorrowed,
                                                       style: ServoComputedValuesBorrowed,
                                                       keyframes: RawGeckoKeyframeListBorrowedMut) -> bool {
     use style::gecko_bindings::structs::Keyframe;
@@ -1648,7 +1648,6 @@ pub extern "C" fn Servo_StyleSet_FillKeyframesForName(raw_data: RawServoStyleSet
 
     let data = PerDocumentStyleData::from_ffi(raw_data).borrow();
     let name = unsafe { Atom::from(name.as_ref().unwrap().as_str_unchecked()) };
-    let style_timing_function = unsafe { timing_function.as_ref().unwrap() };
     let style = ComputedValues::as_arc(&style);
 
     if let Some(ref animation) = data.stylist.animations().get(&name) {
@@ -1659,13 +1658,13 @@ pub extern "C" fn Servo_StyleSet_FillKeyframesForName(raw_data: RawServoStyleSet
           let timing_function = if let Some(val) = step.get_animation_timing_function(&guard) {
               val.into()
           } else {
-              *style_timing_function
+              *timing_function
           };
 
           let keyframe = unsafe {
-                Gecko_AnimationAppendKeyframe(keyframes,
-                                              step.start_percentage.0 as f32,
-                                              &timing_function)
+              Gecko_AnimationAppendKeyframe(keyframes,
+                                            step.start_percentage.0 as f32,
+                                            &timing_function)
           };
 
           fn add_computed_property_value(keyframe: *mut Keyframe,