diff --git a/js/src/jit/Label.h b/js/src/jit/Label.h
index 3286850e47..9f72ab646d 100644
--- a/js/src/jit/Label.h
+++ b/js/src/jit/Label.h
@@ -19,8 +19,8 @@ struct LabelBase
     int32_t offset_ : 31;
     bool bound_   : 1;
 
-    // Disallow assignment.
-    void operator =(const LabelBase& label);
+    void operator =(const LabelBase& label) = delete;
+
   public:
     static const int32_t INVALID_OFFSET = -1;