diff --git a/components/style/properties/helpers/animated_properties.mako.rs b/components/style/properties/helpers/animated_properties.mako.rs
index 7686d1be53a..26e56a89c52 100644
--- a/components/style/properties/helpers/animated_properties.mako.rs
+++ b/components/style/properties/helpers/animated_properties.mako.rs
@@ -723,21 +723,16 @@ impl Animatable for AnimationValue {
         }
     }
 
-    fn get_zero_value(&self) -> Option<Self> {
-        match self {
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        match *self {
             % for prop in data.longhands:
-                % if prop.animatable:
-                    % if prop.animation_value_type == "discrete":
-                        &AnimationValue::${prop.camel_case}(_) => {
-                            None
-                        }
-                    % else:
-                        &AnimationValue::${prop.camel_case}(ref base) => {
-                            base.get_zero_value().map(AnimationValue::${prop.camel_case})
-                        }
-                    % endif
-                % endif
+            % if prop.animatable and prop.animation_value_type != "discrete":
+            AnimationValue::${prop.camel_case}(ref base) => {
+                Ok(AnimationValue::${prop.camel_case}(base.get_zero_value()?))
+            },
+            % endif
             % endfor
+            _ => Err(()),
         }
     }
 
@@ -804,9 +799,8 @@ pub trait Animatable: Sized {
     /// This is not the necessarily the same as the initial value of a property. For example, the
     /// initial value of 'stroke-width' is 1, but the zero value is 0, since adding 1 to the
     /// underlying value will not produce the underlying value.
-    fn get_zero_value(&self) -> Option<Self> {
-        None
-    }
+    #[inline]
+    fn get_zero_value(&self) -> Result<Self, ()> { Err(()) }
 
     /// Compute distance between a value and another for a given property.
     fn compute_distance(&self, _other: &Self) -> Result<f64, ()>  { Err(()) }
@@ -864,7 +858,7 @@ impl Animatable for Au {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(Au(0)) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(Au(0)) }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -917,7 +911,7 @@ impl Animatable for f32 {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(0.) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(0.) }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -933,7 +927,7 @@ impl Animatable for f64 {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(0.) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(0.) }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -949,7 +943,7 @@ impl Animatable for i32 {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(0) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(0) }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -986,7 +980,7 @@ impl Animatable for Percentage {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(Percentage(0.)) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(Percentage(0.)) }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -1172,7 +1166,9 @@ impl Animatable for LengthOrPercentage {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(LengthOrPercentage::zero()) }
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        Ok(LengthOrPercentage::zero())
+    }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -1247,14 +1243,14 @@ impl Animatable for LengthOrPercentageOrAuto {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
+    fn get_zero_value(&self) -> Result<Self, ()> {
         match *self {
             LengthOrPercentageOrAuto::Length(_) |
             LengthOrPercentageOrAuto::Percentage(_) |
             LengthOrPercentageOrAuto::Calc(_) => {
-                Some(LengthOrPercentageOrAuto::Length(Au(0)))
+                Ok(LengthOrPercentageOrAuto::Length(Au(0)))
             },
-            LengthOrPercentageOrAuto::Auto => { None },
+            LengthOrPercentageOrAuto::Auto => Err(()),
         }
     }
 
@@ -1336,14 +1332,14 @@ impl Animatable for LengthOrPercentageOrNone {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
+    fn get_zero_value(&self) -> Result<Self, ()> {
         match *self {
             LengthOrPercentageOrNone::Length(_) |
             LengthOrPercentageOrNone::Percentage(_) |
             LengthOrPercentageOrNone::Calc(_) => {
-                Some(LengthOrPercentageOrNone::Length(Au(0)))
+                Ok(LengthOrPercentageOrNone::Length(Au(0)))
             },
-            LengthOrPercentageOrNone::None => { None },
+            LengthOrPercentageOrNone::None => Err(()),
         }
     }
 
@@ -1450,7 +1446,7 @@ impl Animatable for FontWeight {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(FontWeight::Weight400) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(FontWeight::Weight400) }
 
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
@@ -1513,11 +1509,6 @@ impl Into<FontStretch> for f64 {
     }
 }
 
-// Like std::macros::try!, but for Option<>.
-macro_rules! option_try {
-    ($e:expr) => (match $e { Some(e) => e, None => return None })
-}
-
 /// https://drafts.csswg.org/css-transitions/#animtype-simple-list
 impl<H: Animatable, V: Animatable> Animatable for generic_position::Position<H, V> {
     #[inline]
@@ -1529,10 +1520,10 @@ impl<H: Animatable, V: Animatable> Animatable for generic_position::Position<H,
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
-        Some(generic_position::Position {
-            horizontal: option_try!(self.horizontal.get_zero_value()),
-            vertical: option_try!(self.vertical.get_zero_value()),
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        Ok(generic_position::Position {
+            horizontal: self.horizontal.get_zero_value()?,
+            vertical: self.vertical.get_zero_value()?,
         })
     }
 
@@ -2656,7 +2647,7 @@ impl Animatable for TransformList {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> { Some(TransformList(None)) }
+    fn get_zero_value(&self) -> Result<Self, ()> { Ok(TransformList(None)) }
 }
 
 impl<T, U> Animatable for Either<T, U>
@@ -2679,10 +2670,14 @@ impl<T, U> Animatable for Either<T, U>
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
+    fn get_zero_value(&self) -> Result<Self, ()> {
         match *self {
-            Either::First(ref this) => { this.get_zero_value().map(Either::First) },
-            Either::Second(ref this) => { this.get_zero_value().map(Either::Second) },
+            Either::First(ref this) => {
+                Ok(Either::First(this.get_zero_value()?))
+            },
+            Either::Second(ref this) => {
+                Ok(Either::Second(this.get_zero_value()?))
+            },
         }
     }
 
@@ -2792,8 +2787,8 @@ impl Animatable for IntermediateRGBA {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
-        Some(IntermediateRGBA::transparent())
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        Ok(IntermediateRGBA::transparent())
     }
 
     #[inline]
@@ -2985,10 +2980,10 @@ impl Animatable for IntermediateSVGPaint {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
-        Some(IntermediateSVGPaint {
-            kind: option_try!(self.kind.get_zero_value()),
-            fallback: self.fallback.and_then(|v| v.get_zero_value()),
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        Ok(IntermediateSVGPaint {
+            kind: self.kind.get_zero_value()?,
+            fallback: self.fallback.and_then(|v| v.get_zero_value().ok()),
         })
     }
 }
@@ -3023,14 +3018,15 @@ impl Animatable for IntermediateSVGPaintKind {
     }
 
     #[inline]
-    fn get_zero_value(&self) -> Option<Self> {
-        match self {
-            &SVGPaintKind::Color(ref color) => color.get_zero_value()
-                                                    .map(SVGPaintKind::Color),
-            &SVGPaintKind::None |
-            &SVGPaintKind::ContextFill |
-            &SVGPaintKind::ContextStroke =>  Some(self.clone()),
-            _ => None,
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        match *self {
+            SVGPaintKind::Color(ref color) => {
+                Ok(SVGPaintKind::Color(color.get_zero_value()?))
+            },
+            SVGPaintKind::None |
+            SVGPaintKind::ContextFill |
+            SVGPaintKind::ContextStroke => Ok(self.clone()),
+            _ => Err(()),
         }
     }
 }
diff --git a/components/style/values/animated/effects.rs b/components/style/values/animated/effects.rs
index fb8fb96d3ef..0d5204275a3 100644
--- a/components/style/values/animated/effects.rs
+++ b/components/style/values/animated/effects.rs
@@ -4,7 +4,6 @@
 
 //! Animated types for CSS values related to effects.
 
-use app_units::Au;
 use properties::animated_properties::{Animatable, IntermediateColor};
 use properties::longhands::box_shadow::computed_value::T as ComputedBoxShadowList;
 use properties::longhands::filter::computed_value::T as ComputedFilterList;
@@ -19,10 +18,18 @@ use values::generics::effects::BoxShadow as GenericBoxShadow;
 use values::generics::effects::Filter as GenericFilter;
 use values::generics::effects::SimpleShadow as GenericSimpleShadow;
 
+/// An animated value for the `box-shadow` property.
+pub type BoxShadowList = ShadowList<BoxShadow>;
+
+/// An animated value for the `text-shadow` property.
+pub type TextShadowList = ShadowList<SimpleShadow>;
+
+/// An animated value for shadow lists.
+///
+/// https://drafts.csswg.org/css-transitions/#animtype-shadow-list
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[derive(Clone, Debug, PartialEq)]
-/// An animated value for the `box-shadow` property.
-pub struct BoxShadowList(pub Vec<BoxShadow>);
+pub struct ShadowList<Shadow>(Vec<Shadow>);
 
 /// An animated value for a single `box-shadow`.
 pub type BoxShadow = GenericBoxShadow<IntermediateColor, Length, Length>;
@@ -40,11 +47,6 @@ pub type Filter = GenericFilter<Angle, Number, Length, SimpleShadow>;
 #[cfg(not(feature = "gecko"))]
 pub type Filter = GenericFilter<Angle, Number, Length, Impossible>;
 
-#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Clone, Debug, PartialEq)]
-/// An animated value for the `box-shadow` property.
-pub struct TextShadowList(pub Vec<SimpleShadow>);
-
 /// An animated value for the `drop-shadow()` filter.
 pub type SimpleShadow = GenericSimpleShadow<IntermediateColor, Length, Length>;
 
@@ -53,7 +55,7 @@ impl ToAnimatedValue for ComputedBoxShadowList {
 
     #[inline]
     fn to_animated_value(self) -> Self::AnimatedValue {
-        BoxShadowList(self.0.to_animated_value())
+        ShadowList(self.0.to_animated_value())
     }
 
     #[inline]
@@ -62,8 +64,10 @@ impl ToAnimatedValue for ComputedBoxShadowList {
     }
 }
 
-/// https://drafts.csswg.org/css-transitions/#animtype-shadow-list
-impl Animatable for BoxShadowList {
+impl<S> Animatable for ShadowList<S>
+where
+    S: Animatable + Clone,
+{
     #[inline]
     fn add_weighted(
         &self,
@@ -71,18 +75,6 @@ impl Animatable for BoxShadowList {
         self_portion: f64,
         other_portion: f64,
     ) -> Result<Self, ()> {
-        // The inset value must change
-        let mut zero = BoxShadow {
-            base: SimpleShadow {
-                color: IntermediateColor::transparent(),
-                horizontal: Au(0),
-                vertical: Au(0),
-                blur: Au(0),
-            },
-            spread: Au(0),
-            inset: false,
-        };
-
         let max_len = cmp::max(self.0.len(), other.0.len());
         let mut shadows = Vec::with_capacity(max_len);
         for i in 0..max_len {
@@ -91,23 +83,20 @@ impl Animatable for BoxShadowList {
                     shadow.add_weighted(other, self_portion, other_portion)?
                 },
                 (Some(shadow), None) => {
-                    zero.inset = shadow.inset;
-                    shadow.add_weighted(&zero, self_portion, other_portion)?
+                    shadow.add_weighted(&shadow.get_zero_value()?, self_portion, other_portion)?
                 },
                 (None, Some(shadow)) => {
-                    zero.inset = shadow.inset;
-                    zero.add_weighted(&shadow, self_portion, other_portion)?
+                    shadow.get_zero_value()?.add_weighted(&shadow, self_portion, other_portion)?
                 },
                 (None, None) => unreachable!(),
             });
         }
-
-        Ok(BoxShadowList(shadows))
+        Ok(ShadowList(shadows))
     }
 
     #[inline]
     fn add(&self, other: &Self) -> Result<Self, ()> {
-        Ok(BoxShadowList(
+        Ok(ShadowList(
             self.0.iter().cloned().chain(other.0.iter().cloned()).collect(),
         ))
     }
@@ -118,7 +107,7 @@ impl ToAnimatedValue for ComputedTextShadowList {
 
     #[inline]
     fn to_animated_value(self) -> Self::AnimatedValue {
-        TextShadowList(self.0.to_animated_value())
+        ShadowList(self.0.to_animated_value())
     }
 
     #[inline]
@@ -127,50 +116,6 @@ impl ToAnimatedValue for ComputedTextShadowList {
     }
 }
 
-/// https://drafts.csswg.org/css-transitions/#animtype-shadow-list
-impl Animatable for TextShadowList {
-    #[inline]
-    fn add_weighted(
-        &self,
-        other: &Self,
-        self_portion: f64,
-        other_portion: f64,
-    ) -> Result<Self, ()> {
-        let zero = SimpleShadow {
-            color: IntermediateColor::transparent(),
-            horizontal: Au(0),
-            vertical: Au(0),
-            blur: Au(0),
-        };
-
-        let max_len = cmp::max(self.0.len(), other.0.len());
-        let mut shadows = Vec::with_capacity(max_len);
-        for i in 0..max_len {
-            shadows.push(match (self.0.get(i), other.0.get(i)) {
-                (Some(shadow), Some(other)) => {
-                    shadow.add_weighted(other, self_portion, other_portion)?
-                },
-                (Some(shadow), None) => {
-                    shadow.add_weighted(&zero, self_portion, other_portion)?
-                },
-                (None, Some(shadow)) => {
-                    zero.add_weighted(&shadow, self_portion, other_portion)?
-                },
-                (None, None) => unreachable!(),
-            });
-        }
-
-        Ok(TextShadowList(shadows))
-    }
-
-    #[inline]
-    fn add(&self, other: &Self) -> Result<Self, ()> {
-        Ok(TextShadowList(
-            self.0.iter().cloned().chain(other.0.iter().cloned()).collect(),
-        ))
-    }
-}
-
 impl Animatable for BoxShadow {
     #[inline]
     fn add_weighted(
@@ -189,6 +134,15 @@ impl Animatable for BoxShadow {
         })
     }
 
+    #[inline]
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        Ok(BoxShadow {
+            base: self.base.get_zero_value()?,
+            spread: self.spread.get_zero_value()?,
+            inset: self.inset,
+        })
+    }
+
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
         self.compute_squared_distance(other).map(|sd| sd.sqrt())
@@ -206,7 +160,6 @@ impl Animatable for BoxShadow {
     }
 }
 
-
 impl ToAnimatedValue for ComputedFilterList {
     type AnimatedValue = FilterList;
 
@@ -251,6 +204,16 @@ impl Animatable for SimpleShadow {
         })
     }
 
+    #[inline]
+    fn get_zero_value(&self) -> Result<Self, ()> {
+        Ok(SimpleShadow {
+            color: IntermediateColor::transparent(),
+            horizontal: self.horizontal.get_zero_value()?,
+            vertical: self.vertical.get_zero_value()?,
+            blur: self.blur.get_zero_value()?,
+        })
+    }
+
     #[inline]
     fn compute_distance(&self, other: &Self) -> Result<f64, ()> {
         self.compute_squared_distance(other).map(|sd| sd.sqrt())
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index faf69b35f8d..2fe6f9d806e 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -375,7 +375,7 @@ pub extern "C" fn Servo_AnimationValues_GetZeroValue(
     -> RawServoAnimationValueStrong
 {
     let value_to_match = AnimationValue::as_arc(&value_to_match);
-    if let Some(zero_value) = value_to_match.get_zero_value() {
+    if let Ok(zero_value) = value_to_match.get_zero_value() {
         Arc::new(zero_value).into_strong()
     } else {
         RawServoAnimationValueStrong::null()