diff --git a/components/style/custom_properties.rs b/components/style/custom_properties.rs
index 985179db025..6ed6b6f3288 100644
--- a/components/style/custom_properties.rs
+++ b/components/style/custom_properties.rs
@@ -543,7 +543,6 @@ impl<'a> CustomPropertiesBuilder<'a> {
                 self.may_have_cycles |= !specified_value.references.is_empty();
                 map.insert(name.clone(), (*specified_value).clone());
             },
-            DeclaredValue::WithVariables(_) => unreachable!(),
             DeclaredValue::CSSWideKeyword(keyword) => match keyword {
                 CSSWideKeyword::Initial => {
                     map.remove(name);
diff --git a/components/style/properties/helpers.mako.rs b/components/style/properties/helpers.mako.rs
index e07c9bd57cb..bf262f581d6 100644
--- a/components/style/properties/helpers.mako.rs
+++ b/components/style/properties/helpers.mako.rs
@@ -379,7 +379,6 @@
                         % endif
                     % endif
                 }
-                DeclaredValue::WithVariables(_) => unreachable!(),
                 DeclaredValue::CSSWideKeyword(keyword) => match keyword {
                     % if not data.current_style_struct.inherited:
                     CSSWideKeyword::Unset |
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 39fc90b2f3d..40d2d52541e 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -1444,8 +1444,6 @@ impl ShorthandId {
 pub enum DeclaredValue<'a, T: 'a> {
     /// A known specified value from the stylesheet.
     Value(&'a T),
-    /// An unparsed value that contains `var()` functions.
-    WithVariables(&'a Arc<UnparsedValue>),
     /// An CSS-wide keyword.
     CSSWideKeyword(CSSWideKeyword),
 }
@@ -1459,11 +1457,6 @@ pub enum DeclaredValue<'a, T: 'a> {
 pub enum DeclaredValueOwned<T> {
     /// A known specified value from the stylesheet.
     Value(T),
-    /// An unparsed value that contains `var()` functions.
-    WithVariables(
-        #[cfg_attr(feature = "gecko", ignore_malloc_size_of = "XXX: how to handle this?")]
-        Arc<UnparsedValue>
-    ),
     /// An CSS-wide keyword.
     CSSWideKeyword(CSSWideKeyword),
 }
@@ -1473,7 +1466,6 @@ impl<T> DeclaredValueOwned<T> {
     fn borrow(&self) -> DeclaredValue<T> {
         match *self {
             DeclaredValueOwned::Value(ref v) => DeclaredValue::Value(v),
-            DeclaredValueOwned::WithVariables(ref v) => DeclaredValue::WithVariables(v),
             DeclaredValueOwned::CSSWideKeyword(v) => DeclaredValue::CSSWideKeyword(v),
         }
     }