diff --git a/components/script/dom/cssnamespacerule.rs b/components/script/dom/cssnamespacerule.rs
index e7de369584d..4e93eea2e1f 100644
--- a/components/script/dom/cssnamespacerule.rs
+++ b/components/script/dom/cssnamespacerule.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::Bindings::CSSNamespaceRuleBinding;
+use dom::bindings::codegen::Bindings::CSSNamespaceRuleBinding::CSSNamespaceRuleMethods;
 use dom::bindings::js::Root;
 use dom::bindings::reflector::reflect_dom_object;
 use dom::bindings::str::DOMString;
@@ -38,6 +39,20 @@ impl CSSNamespaceRule {
     }
 }
 
+impl CSSNamespaceRuleMethods for CSSNamespaceRule {
+    // https://drafts.csswg.org/cssom/#dom-cssnamespacerule-prefix
+    fn Prefix(&self) -> DOMString {
+        self.namespacerule.read().prefix
+            .as_ref().map(|s| s.to_string().into())
+            .unwrap_or(DOMString::new())
+    }
+
+    // https://drafts.csswg.org/cssom/#dom-cssnamespacerule-namespaceuri
+    fn NamespaceURI(&self) -> DOMString {
+        (*self.namespacerule.read().url).into()
+    }
+}
+
 impl SpecificCSSRule for CSSNamespaceRule {
     fn ty(&self) -> u16 {
         use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
diff --git a/components/script/dom/webidls/CSSNamespaceRule.webidl b/components/script/dom/webidls/CSSNamespaceRule.webidl
index a8d6b61548f..aa1ce87e289 100644
--- a/components/script/dom/webidls/CSSNamespaceRule.webidl
+++ b/components/script/dom/webidls/CSSNamespaceRule.webidl
@@ -5,6 +5,6 @@
 // https://drafts.csswg.org/cssom/#the-cssnamespacerule-interface
 [Exposed=Window]
 interface CSSNamespaceRule : CSSRule {
-  // readonly attribute DOMString namespaceURI;
-  // readonly attribute DOMString prefix;
+  readonly attribute DOMString namespaceURI;
+  readonly attribute DOMString prefix;
 };
diff --git a/components/style/keyframes.rs b/components/style/keyframes.rs
index b74dd73a4de..884c5fef86b 100644
--- a/components/style/keyframes.rs
+++ b/components/style/keyframes.rs
@@ -10,9 +10,9 @@ use properties::{Importance, PropertyDeclaration, PropertyDeclarationBlock};
 use properties::PropertyDeclarationParseResult;
 use properties::animated_properties::TransitionProperty;
 use std::fmt;
+use servo_url::ServoUrl;
 use std::sync::Arc;
 use stylesheets::{MemoryHoleReporter, Origin};
-use servo_url::ServoUrl;
 use style_traits::ToCss;
 
 /// A number from 1 to 100, indicating the percentage of the animation where