diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index bf06761d6f0..e09fb9e9af0 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -858,7 +858,7 @@ impl<'le> GeckoElement<'le> {
     fn needs_transitions_update_per_property(
         &self,
         longhand_id: LonghandId,
-        combined_duration: f32,
+        combined_duration_seconds: f32,
         before_change_style: &ComputedValues,
         after_change_style: &ComputedValues,
         existing_transitions: &FxHashMap<LonghandId, Arc<AnimationValue>>,
@@ -884,7 +884,7 @@ impl<'le> GeckoElement<'le> {
 
         debug_assert_eq!(to.is_some(), from.is_some());
 
-        combined_duration > 0.0f32 &&
+        combined_duration_seconds > 0.0f32 &&
             from != to &&
             from.unwrap()
                 .animate(
@@ -1533,7 +1533,7 @@ impl<'le> TElement for GeckoElement<'le> {
             transitions_to_keep.insert(physical_longhand);
             if self.needs_transitions_update_per_property(
                 physical_longhand,
-                after_change_ui_style.transition_combined_duration_at(transition_property.index),
+                after_change_ui_style.transition_combined_duration_at(transition_property.index).seconds(),
                 before_change_style,
                 after_change_style,
                 &existing_transitions,
diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index c799ebdb03f..bb134a64ac9 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -39,8 +39,7 @@ use servo_arc::{Arc, RawOffsetArc, UniqueArc};
 use std::mem::{forget, MaybeUninit};
 use std::{cmp, ops, ptr};
 use crate::values::{self, CustomIdent, KeyframesName};
-use crate::values::computed::{Percentage, TransitionProperty};
-use crate::values::computed::BorderStyle;
+use crate::values::computed::{BorderStyle, Percentage, Time, TransitionProperty};
 use crate::values::computed::font::FontSize;
 use crate::values::generics::column::ColumnCount;
 
@@ -1038,14 +1037,13 @@ fn static_assert() {
 
         self.gecko.m${type.capitalize()}${gecko_ffi_name}Count = input_len as u32;
         for (gecko, servo) in self.gecko.m${type.capitalize()}s.iter_mut().take(input_len as usize).zip(v) {
-            gecko.m${gecko_ffi_name} = servo.seconds() * 1000.;
+            gecko.m${gecko_ffi_name} = servo;
         }
     }
     #[allow(non_snake_case)]
     pub fn ${type}_${ident}_at(&self, index: usize)
         -> longhands::${type}_${ident}::computed_value::SingleComputedValue {
-        use crate::values::computed::Time;
-        Time::from_seconds(self.gecko.m${type.capitalize()}s[index].m${gecko_ffi_name} / 1000.)
+        self.gecko.m${type.capitalize()}s[index].m${gecko_ffi_name}
     }
     ${impl_animation_or_transition_count(type, ident, gecko_ffi_name)}
     ${impl_copy_animation_or_transition_value(type, ident, gecko_ffi_name)}
@@ -1772,10 +1770,12 @@ mask-mode mask-repeat mask-clip mask-origin mask-composite mask-position-x mask-
     ${impl_transition_time_value('duration', 'Duration')}
     ${impl_animation_or_transition_timing_function('transition')}
 
-    pub fn transition_combined_duration_at(&self, index: usize) -> f32 {
+    pub fn transition_combined_duration_at(&self, index: usize) -> Time {
         // https://drafts.csswg.org/css-transitions/#transition-combined-duration
-        self.gecko.mTransitions[index % self.gecko.mTransitionDurationCount as usize].mDuration.max(0.0)
-            + self.gecko.mTransitions[index % self.gecko.mTransitionDelayCount as usize].mDelay
+        Time::from_seconds(
+            self.transition_duration_at(index).seconds().max(0.0) +
+            self.transition_delay_at(index).seconds()
+        )
     }
 
     pub fn set_transition_property<I>(&mut self, v: I)
@@ -1818,7 +1818,7 @@ mask-mode mask-repeat mask-clip mask-origin mask-composite mask-position-x mask-
         use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_all_properties;
         if self.gecko.mTransitionPropertyCount == 1 &&
             self.gecko.mTransitions[0].mProperty == eCSSPropertyExtra_all_properties &&
-            self.transition_combined_duration_at(0) <= 0.0f32 {
+            self.transition_combined_duration_at(0).seconds() <= 0.0f32 {
             return false;
         }
 
diff --git a/components/style/values/computed/time.rs b/components/style/values/computed/time.rs
index 5681f6fab5e..1f0a6df018b 100644
--- a/components/style/values/computed/time.rs
+++ b/components/style/values/computed/time.rs
@@ -11,6 +11,7 @@ use style_traits::{CssWriter, ToCss};
 /// A computed `<time>` value.
 #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, PartialOrd, ToResolvedValue)]
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
+#[repr(C)]
 pub struct Time {
     seconds: CSSFloat,
 }
@@ -18,7 +19,7 @@ pub struct Time {
 impl Time {
     /// Creates a time value from a seconds amount.
     pub fn from_seconds(seconds: CSSFloat) -> Self {
-        Time { seconds: seconds }
+        Time { seconds }
     }
 
     /// Returns `0s`.