diff --git a/include/boost/lexical_cast.hpp b/include/boost/lexical_cast.hpp
index 76736a3..2562b62 100644
--- a/include/boost/lexical_cast.hpp
+++ b/include/boost/lexical_cast.hpp
@@ -1526,13 +1526,12 @@ namespace boost {
 
 #if defined(BOOST_NO_STRINGSTREAM)
             typedef std::ostrstream                         out_stream_t;
-            typedef parser_buf<std::strstreambuf, char>     unlocked_but_t;
 #elif defined(BOOST_NO_STD_LOCALE)
             typedef std::ostringstream                      out_stream_t;
-            typedef parser_buf<std::stringbuf, char>        unlocked_but_t;
+            typedef parser_buf<std::streambuf, char>        buffer_t;
 #else
             typedef std::basic_ostringstream<CharT, Traits>                 out_stream_t;
-            typedef parser_buf<std::basic_stringbuf<CharT, Traits>, CharT>  unlocked_but_t;
+            typedef parser_buf<std::basic_streambuf<CharT, Traits>, CharT>  buffer_t;
 #endif
             typedef BOOST_DEDUCED_TYPENAME boost::mpl::if_c<
                 RequiresStringbuffer,
@@ -1615,8 +1614,9 @@ namespace boost {
                 BOOST_STATIC_ASSERT((boost::is_same<char, CharT>::value));
 #endif
                 bool const result = !(out_stream << input).fail();
-                const unlocked_but_t* const p
-                        = static_cast<unlocked_but_t*>(out_stream.rdbuf()) ;
+                const buffer_t* const p = static_cast<buffer_t*>(
+                    static_cast<std::basic_streambuf<CharT, Traits>*>(out_stream.rdbuf())
+                );
                 start = p->pbase();
                 finish = p->pptr();
                 return result;
@@ -1984,15 +1984,13 @@ namespace boost {
                 std::istrstream stream(start, finish - start);
 #else
 
-#if defined(BOOST_NO_STD_LOCALE)
-                std::istringstream stream;
-#else
-                std::basic_istringstream<CharT, Traits> stream;
-#endif // BOOST_NO_STD_LOCALE
-
-                unlocked_but_t buf;
+                buffer_t buf;
                 buf.setbuf(start, finish - start);
-                dynamic_cast<std::basic_ios<CharT, Traits>&>(stream).rdbuf(&buf);
+#if defined(BOOST_NO_STD_LOCALE)
+                std::istream stream(&buf);
+#else
+                std::basic_istream<CharT, Traits> stream(&buf);
+#endif // BOOST_NO_STD_LOCALE
 #endif // BOOST_NO_STRINGSTREAM
 
                 stream.unsetf(std::ios::skipws);