diff --git a/components/fonts/platform/freetype/android/font_list.rs b/components/fonts/platform/freetype/android/font_list.rs
index f8bf939eebd..2f1ecee14ff 100644
--- a/components/fonts/platform/freetype/android/font_list.rs
+++ b/components/fonts/platform/freetype/android/font_list.rs
@@ -432,7 +432,8 @@ where
     let mut produce_font = |font: &Font| {
         let local_font_identifier = LocalFontIdentifier {
             path: Atom::from(FontList::font_absolute_path(&font.filename)),
-            variation_index: 0,
+            face_index: 0,
+            named_instance_index: 0,
         };
         let stretch = StyleFontStretch::NORMAL;
         let weight = font
diff --git a/components/fonts/platform/freetype/font.rs b/components/fonts/platform/freetype/font.rs
index 92998e8ae94..4dfca9cf7c3 100644
--- a/components/fonts/platform/freetype/font.rs
+++ b/components/fonts/platform/freetype/font.rs
@@ -96,7 +96,11 @@ impl PlatformFontMethods for PlatformFont {
         let library = FreeTypeLibraryHandle::get().lock();
         let filename = CString::new(&*font_identifier.path).expect("filename contains NUL byte!");
 
-        let face = FreeTypeFace::new_from_file(&library, &filename, font_identifier.index())?;
+        let face = FreeTypeFace::new_from_file(
+            &library,
+            &filename,
+            font_identifier.face_index_for_freetype(),
+        )?;
 
         let normalized_variations = face.set_variations_for_font(variations, &library)?;
 
diff --git a/components/fonts/platform/freetype/font_list.rs b/components/fonts/platform/freetype/font_list.rs
index 585daa84177..57759e20f91 100644
--- a/components/fonts/platform/freetype/font_list.rs
+++ b/components/fonts/platform/freetype/font_list.rs
@@ -123,7 +123,8 @@ where
 
             let local_font_identifier = LocalFontIdentifier {
                 path: Atom::from(c_str_to_string(path as *const c_char)),
-                variation_index: index as i32,
+                face_index: (index & 0xFFFF) as u16,
+                named_instance_index: (index >> 16) as u16,
             };
             let descriptor = FontTemplateDescriptor::new(weight, stretch, style);
 
diff --git a/components/fonts/platform/freetype/ohos/font_list.rs b/components/fonts/platform/freetype/ohos/font_list.rs
index f3776f951b7..345a2b6827c 100644
--- a/components/fonts/platform/freetype/ohos/font_list.rs
+++ b/components/fonts/platform/freetype/ohos/font_list.rs
@@ -444,7 +444,8 @@ where
     let mut produce_font = |font: &Font| {
         let local_font_identifier = LocalFontIdentifier {
             path: Atom::from(font.filepath.clone()),
-            variation_index: 0,
+            face_index: 0,
+            named_instance_index: 0,
         };
         let stretch = font.width.into();
         let weight = font
diff --git a/components/fonts/tests/font_context.rs b/components/fonts/tests/font_context.rs
index a9e3a3f9b25..8b78cf60df6 100644
--- a/components/fonts/tests/font_context.rs
+++ b/components/fonts/tests/font_context.rs
@@ -186,7 +186,8 @@ mod font_context {
 
             let local_font_identifier = LocalFontIdentifier {
                 path: path.to_str().expect("Could not load test font").into(),
-                variation_index: 0,
+                face_index: 0,
+                named_instance_index: 0,
             };
             let handle = PlatformFont::new_from_local_font_identifier(
                 local_font_identifier.clone(),
diff --git a/components/shared/fonts/font_identifier.rs b/components/shared/fonts/font_identifier.rs
index 00050c968c1..8029252a20c 100644
--- a/components/shared/fonts/font_identifier.rs
+++ b/components/shared/fonts/font_identifier.rs
@@ -41,18 +41,26 @@ mod platform {
         /// The path to the font.
         pub path: Atom,
         /// The variation index within the font.
-        pub variation_index: i32,
+        pub face_index: u16,
+        /// The index of the named instance within the font.
+        ///
+        /// For non-variable fonts, this is ignored.
+        pub named_instance_index: u16,
     }
 
     impl LocalFontIdentifier {
         pub fn index(&self) -> u32 {
-            self.variation_index.try_into().unwrap()
+            self.face_index as u32
+        }
+
+        pub fn named_instance_index(&self) -> u32 {
+            self.named_instance_index as u32
         }
 
         pub fn native_font_handle(&self) -> NativeFontHandle {
             NativeFontHandle {
                 path: PathBuf::from(&*self.path),
-                index: self.variation_index as u32,
+                index: self.face_index as u32,
             }
         }
 
@@ -64,9 +72,20 @@ mod platform {
 
             Some(FontDataAndIndex {
                 data,
-                index: self.variation_index as u32,
+                index: self.face_index as u32,
             })
         }
+
+        /// Fontconfig and FreeType use a packed format to represent face and
+        /// named instance indexes in a single integer. The first 16 bits make
+        /// up the named instance index and the second 16 bits make up the
+        /// face index.
+        ///
+        /// See <https://freetype.org/freetype2/docs/reference/ft2-face_creation.html#ft_open_face>
+        /// for more information.
+        pub fn face_index_for_freetype(&self) -> u32 {
+            ((self.named_instance_index()) << 16) | self.index()
+        }
     }
 }