diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index 59feddfcc22..93e46d14510 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -1221,7 +1221,6 @@ impl XMLHttpRequest {
         }
     }
 
-    #[allow(dead_code)]
     fn final_mime_type(&self) -> Option<Mime> {
         if self.override_mime_type.borrow().is_some() {
             self.override_mime_type.borrow().clone()