diff --git a/ql/instruments/basketoption.hpp b/ql/instruments/basketoption.hpp
index fd0ee4bd12..3e8c483765 100644
--- a/ql/instruments/basketoption.hpp
+++ b/ql/instruments/basketoption.hpp
@@ -80,7 +80,7 @@ namespace QuantLib {
                                       a.begin(), Real(0.0));
         }
 
-        Array weights() const { return weights_; }
+        const Array& weights() const { return weights_; }
 
       private:
         Array weights_;