diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 5f5b0bda04a..38b08e0ba25 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -17,7 +17,7 @@ use dom::bindings::codegen::Bindings::WindowBinding::{self, FrameRequestCallback
 use dom::bindings::codegen::Bindings::WindowBinding::{ScrollBehavior, ScrollToOptions};
 use dom::bindings::codegen::UnionTypes::RequestOrUSVString;
 use dom::bindings::error::{Error, ErrorResult, Fallible};
-use dom::bindings::global::{GlobalRef, global_root_from_object};
+use dom::bindings::global::global_scope_from_object;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root};
 use dom::bindings::num::Finite;
@@ -1496,10 +1496,9 @@ impl Window {
     /// in a top-level `Window` global.
     #[allow(unsafe_code)]
     pub unsafe fn global_is_mozbrowser(_: *mut JSContext, obj: HandleObject) -> bool {
-        match global_root_from_object(obj.get()).r() {
-            GlobalRef::Window(window) => window.is_mozbrowser(),
-            _ => false,
-        }
+        global_scope_from_object(obj.get())
+            .downcast::<Window>()
+            .map_or(false, |window| window.is_mozbrowser())
     }
 
     #[allow(unsafe_code)]