diff --git a/components/style/gecko/media_queries.rs b/components/style/gecko/media_queries.rs
index 556470569db..87663473542 100644
--- a/components/style/gecko/media_queries.rs
+++ b/components/style/gecko/media_queries.rs
@@ -213,12 +213,11 @@ impl Device {
             None => return MediaType::screen(),
         };
 
-        // Gecko allows emulating random media with mIsEmulatingMedia and
-        // mMediaEmulated.
-        let medium_to_use = if pc.mIsEmulatingMedia() != 0 {
+        // Gecko allows emulating random media with mMediaEmulated.
+        let medium_to_use = if !pc.mMediaEmulated.mRawPtr.is_null() {
             pc.mMediaEmulated.mRawPtr
         } else {
-            pc.mMedium
+            pc.mMedium as *const bindings::nsAtom as *mut _
         };
 
         MediaType(CustomIdent(unsafe { Atom::from_raw(medium_to_use) }))