diff --git a/components/style/values/computed/text.rs b/components/style/values/computed/text.rs
index 3f9ffb2ad0f..57a142860d9 100644
--- a/components/style/values/computed/text.rs
+++ b/components/style/values/computed/text.rs
@@ -28,7 +28,7 @@ pub use crate::values::specified::{TextDecorationSkipInk, TextTransform};
 pub type InitialLetter = GenericInitialLetter<CSSFloat, CSSInteger>;
 
 /// Implements type for `text-underline-offset` and `text-decoration-thickness` properties
-pub type TextDecorationLength = GenericTextDecorationLength<Length>;
+pub type TextDecorationLength = GenericTextDecorationLength<LengthPercentage>;
 
 /// A computed value for the `letter-spacing` property.
 #[repr(transparent)]
diff --git a/components/style/values/generics/text.rs b/components/style/values/generics/text.rs
index fd434cc1273..6ad983e00f9 100644
--- a/components/style/values/generics/text.rs
+++ b/components/style/values/generics/text.rs
@@ -124,7 +124,7 @@ impl<N, L> LineHeight<N, L> {
 }
 
 /// Implements type for text-underline-offset and text-decoration-thickness
-/// which take the grammar of auto | from-font | <length>
+/// which take the grammar of auto | from-font | <length> | <percentage>
 ///
 /// https://drafts.csswg.org/css-text-decor-4/
 #[repr(C, u8)]
@@ -148,7 +148,7 @@ impl<N, L> LineHeight<N, L> {
 )]
 #[allow(missing_docs)]
 pub enum GenericTextDecorationLength<L> {
-    Length(L),
+    LengthPercentage(L),
     Auto,
     FromFont,
 }
diff --git a/components/style/values/specified/text.rs b/components/style/values/specified/text.rs
index 16df2fa4b4e..835fefa292a 100644
--- a/components/style/values/specified/text.rs
+++ b/components/style/values/specified/text.rs
@@ -1030,7 +1030,7 @@ pub enum TextDecorationSkipInk {
 }
 
 /// Implements type for `text-underline-offset` and `text-decoration-thickness` properties
-pub type TextDecorationLength = GenericTextDecorationLength<Length>;
+pub type TextDecorationLength = GenericTextDecorationLength<LengthPercentage>;
 
 impl TextDecorationLength {
     /// `Auto` value.