diff --git a/components/style/values/specified/grid.rs b/components/style/values/specified/grid.rs
index c0b11ddf146c..97d4f9ed5f0c 100644
--- a/components/style/values/specified/grid.rs
+++ b/components/style/values/specified/grid.rs
@@ -2,14 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-//! A grid line type.
+//! Necessary types for [grid](https://drafts.csswg.org/css-grid/).
 
 use cssparser::{Parser, Token};
 use parser::{Parse, ParserContext};
 use std::fmt;
 use style_traits::ToCss;
 use values::{CSSFloat, HasViewportPercentage};
-use values::computed::ComputedValueAsSpecified;
+use values::computed::{ComputedValueAsSpecified, Context, ToComputedValue};
 use values::specified::LengthOrPercentage;
 
 #[derive(PartialEq, Clone, Debug)]
@@ -159,6 +159,29 @@ impl HasViewportPercentage for TrackBreadth<LengthOrPercentage> {
     }
 }
 
+impl<L: ToComputedValue> ToComputedValue for TrackBreadth<L> {
+    type ComputedValue = TrackBreadth<L::ComputedValue>;
+
+    #[inline]
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        match *self {
+            TrackBreadth::Breadth(ref lop) => TrackBreadth::Breadth(lop.to_computed_value(context)),
+            TrackBreadth::Flex(fr) => TrackBreadth::Flex(fr),
+            TrackBreadth::Keyword(k) => TrackBreadth::Keyword(k),
+        }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        match *computed {
+            TrackBreadth::Breadth(ref lop) =>
+                TrackBreadth::Breadth(ToComputedValue::from_computed_value(lop)),
+            TrackBreadth::Flex(fr) => TrackBreadth::Flex(fr),
+            TrackBreadth::Keyword(k) => TrackBreadth::Keyword(k),
+        }
+    }
+}
+
 #[allow(missing_docs)]
 #[derive(Clone, PartialEq, Debug)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
@@ -229,3 +252,30 @@ impl HasViewportPercentage for TrackSize<LengthOrPercentage> {
         }
     }
 }
+
+impl<L: ToComputedValue> ToComputedValue for TrackSize<L> {
+    type ComputedValue = TrackSize<L::ComputedValue>;
+
+    #[inline]
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        match *self {
+            TrackSize::Breadth(ref b) => TrackSize::Breadth(b.to_computed_value(context)),
+            TrackSize::MinMax(ref b_1, ref b_2) =>
+                TrackSize::MinMax(b_1.to_computed_value(context), b_2.to_computed_value(context)),
+            TrackSize::FitContent(ref lop) => TrackSize::FitContent(lop.to_computed_value(context)),
+        }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        match *computed {
+            TrackSize::Breadth(ref b) =>
+                TrackSize::Breadth(ToComputedValue::from_computed_value(b)),
+            TrackSize::MinMax(ref b_1, ref b_2) =>
+                TrackSize::MinMax(ToComputedValue::from_computed_value(b_1),
+                                  ToComputedValue::from_computed_value(b_2)),
+            TrackSize::FitContent(ref lop) =>
+                TrackSize::FitContent(ToComputedValue::from_computed_value(lop)),
+        }
+    }
+}
diff --git a/components/style/values/specified/mod.rs b/components/style/values/specified/mod.rs
index 64c25c2d509d..d6b4842e59c1 100644
--- a/components/style/values/specified/mod.rs
+++ b/components/style/values/specified/mod.rs
@@ -22,7 +22,7 @@ use super::computed::Shadow as ComputedShadow;
 
 #[cfg(feature = "gecko")]
 pub use self::align::{AlignItems, AlignJustifyContent, AlignJustifySelf, JustifyItems};
-pub use self::grid::GridLine;
+pub use self::grid::{GridLine, TrackBreadth, TrackKeyword, TrackSize};
 pub use self::image::{AngleOrCorner, ColorStop, EndingShape as GradientEndingShape, Gradient};
 pub use self::image::{GradientKind, HorizontalDirection, Image, LengthOrKeyword, LengthOrPercentageOrKeyword};
 pub use self::image::{SizeKeyword, VerticalDirection};