diff --git a/components/script/Cargo.toml b/components/script/Cargo.toml
index c7463e73a53..8e62705f434 100644
--- a/components/script/Cargo.toml
+++ b/components/script/Cargo.toml
@@ -90,3 +90,4 @@ euclid = "0.2"
 tendril = "0.1.1"
 rand = "0.3"
 serde = "0.6"
+caseless = "0.1.0"
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index a07529ebbec..86d02d462c3 100644
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -2,6 +2,7 @@
  * 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/. */
 
+use caseless::compatibility_caseless_match_str;
 use dom::activation::Activatable;
 use dom::attr::{Attr, AttrValue};
 use dom::bindings::cell::DOMRefCell;
@@ -388,9 +389,8 @@ fn in_same_group(other: &HTMLInputElement, owner: Option<&HTMLFormElement>,
     other.input_type.get() == InputType::InputRadio &&
     // TODO Both a and b are in the same home subtree.
     other_owner == owner &&
-    // TODO should be a unicode compatibility caseless match
     match (other.get_radio_group_name(), group) {
-        (Some(ref s1), Some(s2)) => s1 == s2 && s2 != &atom!(""),
+        (Some(ref s1), Some(s2)) => compatibility_caseless_match_str(s1, s2) && s2 != &atom!(""),
         _ => false
     }
 }
diff --git a/components/script/lib.rs b/components/script/lib.rs
index 6ebf3d12df6..c35e6fbe753 100644
--- a/components/script/lib.rs
+++ b/components/script/lib.rs
@@ -46,6 +46,7 @@ extern crate util;
 extern crate angle;
 extern crate canvas;
 extern crate canvas_traits;
+extern crate caseless;
 extern crate core;
 extern crate cssparser;
 extern crate devtools_traits;
diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 08672e8af2b..18caf480cec 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -167,6 +167,15 @@ dependencies = [
  "util 0.0.1",
 ]
 
+[[package]]
+name = "caseless"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "regex 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-normalization 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "cgl"
 version = "0.1.0"
@@ -1442,6 +1451,7 @@ dependencies = [
  "bitflags 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "canvas 0.0.1",
  "canvas_traits 0.0.1",
+ "caseless 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "cssparser 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "devtools_traits 0.0.1",
  "encoding 0.2.32 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1780,6 +1790,11 @@ dependencies = [
  "matches 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "unicode-normalization"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "unicode-script"
 version = "0.1.1"
diff --git a/tests/wpt/metadata/html/semantics/forms/the-input-element/radio-groupname-case.html.ini b/tests/wpt/metadata/html/semantics/forms/the-input-element/radio-groupname-case.html.ini
index 23d89442303..4de30f16232 100644
--- a/tests/wpt/metadata/html/semantics/forms/the-input-element/radio-groupname-case.html.ini
+++ b/tests/wpt/metadata/html/semantics/forms/the-input-element/radio-groupname-case.html.ini
@@ -1,23 +1,5 @@
 [radio-groupname-case.html]
   type: testharness
-  [radio button group name = sImPlE]
-    expected: FAIL
-
   [radio button group name = paSSfield-killroyß]
     expected: FAIL
 
-  [radio button group name = глупый]
-    expected: FAIL
-
-  [radio button group name = åωk]
-    expected: FAIL
-
-  [radio button group name = blah1]
-    expected: FAIL
-
-  [radio button group name = tÉdz5アパートFi]
-    expected: FAIL
-
-  [radio button group name = ΣΣ]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/semantics/forms/the-input-element/radio.html.ini b/tests/wpt/metadata/html/semantics/forms/the-input-element/radio.html.ini
index 59a2ba43d2a..212ef8ec4a3 100644
--- a/tests/wpt/metadata/html/semantics/forms/the-input-element/radio.html.ini
+++ b/tests/wpt/metadata/html/semantics/forms/the-input-element/radio.html.ini
@@ -3,6 +3,3 @@
   [canceled activation steps on unchecked radio]
     expected: FAIL
 
-  [radio inputs with name attributes groüp2 and groÜp2 belong to the same radio button group]
-    expected: FAIL
-