1 files changed, 4 insertions, 3 deletions
diff --git a/components/script/dom/cssmediarule.rs b/components/script/dom/cssmediarule.rs
index a8d8649b31f..67933fccd3b 100644
--- a/components/script/dom/cssmediarule.rs
+++ b/components/script/dom/cssmediarule.rs
@@ -23,15 +23,16 @@ pub struct CSSMediaRule {
 }
 
 impl CSSMediaRule {
-    fn new_inherited(parent: &CSSStyleSheet, mediarule: Arc<RwLock<MediaRule>>) -> CSSMediaRule {
+    fn new_inherited(parent: Option<&CSSStyleSheet>, mediarule: Arc<RwLock<MediaRule>>) -> CSSMediaRule {
+        let list = mediarule.read().rules.clone();
         CSSMediaRule {
-            cssrule: CSSGroupingRule::new_inherited(parent),
+            cssrule: CSSGroupingRule::new_inherited(parent, list),
             mediarule: mediarule,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: &CSSStyleSheet,
+    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
                mediarule: Arc<RwLock<MediaRule>>) -> Root<CSSMediaRule> {
         reflect_dom_object(box CSSMediaRule::new_inherited(parent, mediarule),
                            window,