diff --git a/include/boost/system/detail/system_category_win32.hpp b/include/boost/system/detail/system_category_win32.hpp
index 4739b89..8a86e81 100644
--- a/include/boost/system/detail/system_category_win32.hpp
+++ b/include/boost/system/detail/system_category_win32.hpp
@@ -55,6 +55,19 @@ inline char const * unknown_message_win32( int ev, char * buffer, std::size_t le
 
 #endif
 
+inline boost::winapi::UINT_ message_cp_win32()
+{
+#if defined(BOOST_SYSTEM_USE_UTF8)
+
+    return boost::winapi::CP_UTF8_;
+
+#else
+
+    return boost::winapi::CP_ACP_;
+
+#endif
+}
+
 inline char const * system_category_message_win32( int ev, char * buffer, std::size_t len ) BOOST_NOEXCEPT
 {
     if( len == 0 )
@@ -95,7 +108,9 @@ inline char const * system_category_message_win32( int ev, char * buffer, std::s
         return unknown_message_win32( ev, buffer, len );
     }
 
-    int r = boost::winapi::WideCharToMultiByte( CP_ACP_, 0, wbuffer, -1, buffer, static_cast<int>( len ), NULL, NULL );
+    UINT_ const code_page = message_cp_win32();
+
+    int r = boost::winapi::WideCharToMultiByte( code_page, 0, wbuffer, -1, buffer, static_cast<int>( len ), NULL, NULL );
 
     if( r == 0 )
     {
@@ -155,8 +170,11 @@ inline std::string system_category_message_win32( int ev )
     }
 
     local_free lf_ = { lpMsgBuf };
+    (void)lf_;
 
-    int r = boost::winapi::WideCharToMultiByte( CP_ACP_, 0, lpMsgBuf, -1, 0, 0, NULL, NULL );
+    UINT_ const code_page = message_cp_win32();
+
+    int r = boost::winapi::WideCharToMultiByte( code_page, 0, lpMsgBuf, -1, 0, 0, NULL, NULL );
 
     if( r == 0 )
     {
@@ -165,7 +183,7 @@ inline std::string system_category_message_win32( int ev )
 
     std::string buffer( r, char() );
 
-    r = boost::winapi::WideCharToMultiByte( CP_ACP_, 0, lpMsgBuf, -1, &buffer[0], r, NULL, NULL );
+    r = boost::winapi::WideCharToMultiByte( code_page, 0, lpMsgBuf, -1, &buffer[0], r, NULL, NULL );
 
     if( r == 0 )
     {
diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index 3964569..1562e4b 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -278,7 +278,8 @@ public:
 
     // clang++ 3.8 and below: initialization of const object
     // requires a user-provided default constructor
-    BOOST_SYSTEM_CONSTEXPR generic_error_category() BOOST_NOEXCEPT: error_category( 0xB2AB117A257EDF0Dull )
+    BOOST_SYSTEM_CONSTEXPR generic_error_category() BOOST_NOEXCEPT:
+        error_category( ( boost::ulong_long_type( 0xB2AB117A ) << 32 ) + 0x257EDF0D )
     {
     }
 
@@ -295,7 +296,8 @@ class BOOST_SYMBOL_VISIBLE system_error_category: public error_category
 {
 public:
 
-    BOOST_SYSTEM_CONSTEXPR system_error_category() BOOST_NOEXCEPT: error_category( 0x8FAFD21E25C5E09Bull )
+    BOOST_SYSTEM_CONSTEXPR system_error_category() BOOST_NOEXCEPT:
+        error_category( ( boost::ulong_long_type( 0x8FAFD21E ) << 32 ) + 0x25C5E09B )
     {
     }
 
@@ -651,7 +653,7 @@ public:
         return failed_? unspecified_bool_true: 0;
     }
 
-    BOOST_SYSTEM_CONSTEXPR bool operator!() const  BOOST_NOEXCEPT // true if no error
+    BOOST_SYSTEM_CONSTEXPR bool operator!() const BOOST_NOEXCEPT // true if no error
     {
         return !failed_;
     }
@@ -773,8 +775,8 @@ inline std::size_t hash_value( error_code const & ec )
         id = reinterpret_cast<boost::ulong_long_type>( &cat );
     }
 
-    boost::ulong_long_type hv = 0xCBF29CE484222325ull;
-    boost::ulong_long_type const prime = 0x00000100000001B3ull;
+    boost::ulong_long_type hv = ( boost::ulong_long_type( 0xCBF29CE4 ) << 32 ) + 0x84222325;
+    boost::ulong_long_type const prime = ( boost::ulong_long_type( 0x00000100 ) << 32 ) + 0x000001B3;
 
     // id
 
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index ee73b6b..8b6ee0a 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -132,3 +132,5 @@ system-run- failed_constexpr_test.cpp ;
 
 # Quick (CI) test
 run quick.cpp ;
+
+run quick.cpp : : : <warnings>all <warnings-as-errors>on : warnings_test ;