diff --git a/components/script/dom/attr.rs b/components/script/dom/attr.rs
index c25c9d4d611..aef9d65e5ff 100644
--- a/components/script/dom/attr.rs
+++ b/components/script/dom/attr.rs
@@ -101,7 +101,7 @@ pub struct Attr {
     value: DOMRefCell<AttrValue>,
     name: Atom,
     namespace: Namespace,
-    prefix: Option<DOMString>,
+    prefix: Option<Atom>,
 
     /// the element that owns this attribute.
     owner: MutNullableHeap<JS<Element>>,
@@ -116,7 +116,7 @@ impl Attr {
             value: DOMRefCell::new(value),
             name: name,
             namespace: namespace,
-            prefix: prefix,
+            prefix: prefix.map(|p| Atom::from_slice(&p)),
             owner: MutNullableHeap::new(owner.map(JS::from_rooted)),
         }
     }
@@ -141,7 +141,7 @@ impl Attr {
     }
 
     #[inline]
-    pub fn prefix<'a>(&'a self) -> &'a Option<DOMString> {
+    pub fn prefix<'a>(&'a self) -> &'a Option<Atom> {
         &self.prefix
     }
 }
@@ -205,7 +205,7 @@ impl<'a> AttrMethods for JSRef<'a, Attr> {
 
     // https://dom.spec.whatwg.org/#dom-attr-prefix
     fn GetPrefix(self) -> Option<DOMString> {
-        self.prefix.clone()
+        self.prefix().as_ref().map(|p| (**p).to_owned())
     }
 
     // https://dom.spec.whatwg.org/#dom-attr-ownerelement
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 525130af9fc..8d5c2184c0f 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -1778,7 +1778,7 @@ impl Node {
                         &Attr::new(window.r(),
                                    attr.r().local_name().clone(), attr.r().value().clone(),
                                    attr.r().name().clone(), attr.r().namespace().clone(),
-                                   attr.r().prefix().clone(), Some(copy_elem)));
+                                   attr.r().GetPrefix(), Some(copy_elem)));
                 }
             },
             _ => ()