diff --git a/components/style/values/computed/length.rs b/components/style/values/computed/length.rs
index 535219d187d..f765b1ae5b6 100644
--- a/components/style/values/computed/length.rs
+++ b/components/style/values/computed/length.rs
@@ -278,7 +278,9 @@ impl ToComputedValue for specified::CalcLengthOrPercentage {
 #[animate(fallback = "Self::animate_fallback")]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[css(derive_debug)]
-#[derive(Animate, Clone, Copy, PartialEq, ToAnimatedZero, ToCss)]
+#[derive(Animate, Clone, ComputeSquaredDistance, Copy, PartialEq)]
+#[derive(ToAnimatedZero, ToCss)]
+#[distance(fallback = "Self::compute_squared_distance_fallback")]
 pub enum LengthOrPercentage {
     Length(Au),
     Percentage(Percentage),
@@ -304,22 +306,16 @@ impl LengthOrPercentage {
         let other = CalcLengthOrPercentage::from(*other);
         Ok(LengthOrPercentage::Calc(this.animate(&other, procedure)?))
     }
-}
 
-impl ComputeSquaredDistance for LengthOrPercentage {
     #[inline]
-    fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
-        match (self, other) {
-            (&LengthOrPercentage::Length(ref this), &LengthOrPercentage::Length(ref other)) => {
-                this.compute_squared_distance(other)
-            },
-            (&LengthOrPercentage::Percentage(ref this), &LengthOrPercentage::Percentage(ref other)) => {
-                this.compute_squared_distance(other)
-            },
-            (this, other) => {
-                CalcLengthOrPercentage::compute_squared_distance(&(*this).into(), &(*other).into())
-            }
-        }
+    fn compute_squared_distance_fallback(
+        &self,
+        other: &Self,
+    ) -> Result<SquaredDistance, ()> {
+        CalcLengthOrPercentage::compute_squared_distance(
+            &(*self).into(),
+            &(*other).into(),
+        )
     }
 }
 
@@ -432,7 +428,8 @@ impl ToComputedValue for specified::LengthOrPercentage {
 #[animate(fallback = "Self::animate_fallback")]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[css(derive_debug)]
-#[derive(Animate, Clone, Copy, PartialEq, ToCss)]
+#[derive(Animate, Clone, ComputeSquaredDistance, Copy, PartialEq, ToCss)]
+#[distance(fallback = "Self::compute_squared_distance_fallback")]
 pub enum LengthOrPercentageOrAuto {
     Length(Au),
     Percentage(Percentage),
@@ -453,22 +450,16 @@ impl LengthOrPercentageOrAuto {
             this.animate(&other, procedure)?.ok_or(())?,
         ))
     }
-}
 
-impl ComputeSquaredDistance for LengthOrPercentageOrAuto {
     #[inline]
-    fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
-        match (self, other) {
-            (&LengthOrPercentageOrAuto::Length(ref this), &LengthOrPercentageOrAuto::Length(ref other)) => {
-                this.compute_squared_distance(other)
-            },
-            (&LengthOrPercentageOrAuto::Percentage(ref this), &LengthOrPercentageOrAuto::Percentage(ref other)) => {
-                this.compute_squared_distance(other)
-            },
-            (this, other) => {
-                <Option<CalcLengthOrPercentage>>::compute_squared_distance(&(*this).into(), &(*other).into())
-            }
-        }
+    fn compute_squared_distance_fallback(
+        &self,
+        other: &Self,
+    ) -> Result<SquaredDistance, ()> {
+        <Option<CalcLengthOrPercentage>>::compute_squared_distance(
+            &(*self).into(),
+            &(*other).into(),
+        )
     }
 }
 
@@ -533,7 +524,8 @@ impl ToComputedValue for specified::LengthOrPercentageOrAuto {
 #[animate(fallback = "Self::animate_fallback")]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[css(derive_debug)]
-#[derive(Animate, Clone, Copy, PartialEq, ToCss)]
+#[derive(Animate, Clone, ComputeSquaredDistance, Copy, PartialEq, ToCss)]
+#[distance(fallback = "Self::compute_squared_distance_fallback")]
 pub enum LengthOrPercentageOrNone {
     Length(Au),
     Percentage(Percentage),
@@ -554,22 +546,15 @@ impl LengthOrPercentageOrNone {
             this.animate(&other, procedure)?.ok_or(())?,
         ))
     }
-}
 
-impl ComputeSquaredDistance for LengthOrPercentageOrNone {
-    #[inline]
-    fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
-        match (self, other) {
-            (&LengthOrPercentageOrNone::Length(ref this), &LengthOrPercentageOrNone::Length(ref other)) => {
-                this.compute_squared_distance(other)
-            },
-            (&LengthOrPercentageOrNone::Percentage(ref this), &LengthOrPercentageOrNone::Percentage(ref other)) => {
-                this.compute_squared_distance(other)
-            },
-            (this, other) => {
-                <Option<CalcLengthOrPercentage>>::compute_squared_distance(&(*this).into(), &(*other).into())
-            }
-        }
+    fn compute_squared_distance_fallback(
+        &self,
+        other: &Self,
+    ) -> Result<SquaredDistance, ()> {
+        <Option<CalcLengthOrPercentage>>::compute_squared_distance(
+            &(*self).into(),
+            &(*other).into(),
+        )
     }
 }
 
diff --git a/components/style_derive/compute_squared_distance.rs b/components/style_derive/compute_squared_distance.rs
index 0cc19d2d737..cbdd9c62acc 100644
--- a/components/style_derive/compute_squared_distance.rs
+++ b/components/style_derive/compute_squared_distance.rs
@@ -4,15 +4,16 @@
 
 use animate::AnimationVariantAttrs;
 use cg;
-use quote;
-use syn;
+use quote::Tokens;
+use syn::{DeriveInput, Path};
 
-pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
+pub fn derive(input: DeriveInput) -> Tokens {
     let name = &input.ident;
     let trait_path = &["values", "distance", "ComputeSquaredDistance"];
     let (impl_generics, ty_generics, mut where_clause) =
         cg::trait_parts(&input, trait_path);
 
+    let input_attrs = cg::parse_input_attrs::<DistanceInputAttrs>(&input);
     let variants = cg::variants(&input);
     let mut match_body = quote!();
     let mut append_error_clause = variants.len() > 1;
@@ -45,7 +46,13 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
     }));
 
     if append_error_clause {
-        match_body = quote! { #match_body, _ => Err(()), };
+        if let Some(fallback) = input_attrs.fallback {
+            match_body.append(quote! {
+                (this, other) => #fallback(this, other)
+            });
+        } else {
+            match_body.append(quote! { _ => Err(()) });
+        }
     }
 
     quote! {
@@ -63,3 +70,9 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
         }
     }
 }
+
+#[darling(attributes(distance), default)]
+#[derive(Default, FromDeriveInput)]
+struct DistanceInputAttrs {
+    fallback: Option<Path>,
+}
diff --git a/components/style_derive/lib.rs b/components/style_derive/lib.rs
index a0e09477c57..f98829e60bf 100644
--- a/components/style_derive/lib.rs
+++ b/components/style_derive/lib.rs
@@ -25,7 +25,7 @@ pub fn derive_animate(stream: TokenStream) -> TokenStream {
     animate::derive(input).to_string().parse().unwrap()
 }
 
-#[proc_macro_derive(ComputeSquaredDistance, attributes(animation))]
+#[proc_macro_derive(ComputeSquaredDistance, attributes(animation, distance))]
 pub fn derive_compute_squared_distance(stream: TokenStream) -> TokenStream {
     let input = syn::parse_derive_input(&stream.to_string()).unwrap();
     compute_squared_distance::derive(input).to_string().parse().unwrap()