diff --git a/include/boost/core/string_view.hpp b/include/boost/core/string_view.hpp
index 2aae97b..4272b69 100644
--- a/include/boost/core/string_view.hpp
+++ b/include/boost/core/string_view.hpp
@@ -383,23 +383,11 @@ public:
 
     // conversions
 
-#if !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS)
-
-    template<class Ch2, class En = typename boost::enable_if<is_same<Ch2, Ch> >::type>
-    operator std::basic_string<Ch2>() const
+    template<class A> operator std::basic_string<Ch, std::char_traits<Ch>, A>() const
     {
-        return std::basic_string<Ch>( data(), size() );
+        return std::basic_string<Ch, std::char_traits<Ch>, A>( data(), size() );
     }
 
-#else
-
-    operator std::basic_string<Ch>() const
-    {
-        return std::basic_string<Ch>( data(), size() );
-    }
-
-#endif
-
 #if !defined(BOOST_NO_CXX17_HDR_STRING_VIEW)
 
     template<class Ch2, class En = typename boost::enable_if<is_same<Ch2, Ch> >::type>