diff --git a/include/etl/functional.h b/include/etl/functional.h
index a540f3a7..b00835f5 100644
--- a/include/etl/functional.h
+++ b/include/etl/functional.h
@@ -62,7 +62,7 @@ namespace etl
       return *t;
     }
 
-    reference_wrapper<T>& operator = (T value)
+    reference_wrapper<T>& operator = (T& value)
     {
       *t = value;
       return *this;