Index: include/valarray
===================================================================
--- include/valarray
+++ include/valarray
@@ -2730,7 +2730,7 @@
 };
 
 template<class _ValExpr>
-__val_expr<_ValExpr>::operator valarray<__val_expr::result_type>() const
+__val_expr<_ValExpr>::operator valarray<typename __val_expr<_ValExpr>::result_type>() const
 {
     valarray<result_type> __r;
     size_t __n = __expr_.size();