diff --git a/include/libtorrent/utf8.hpp b/include/libtorrent/utf8.hpp
index 2a812b5d9..d0da1a686 100644
--- a/include/libtorrent/utf8.hpp
+++ b/include/libtorrent/utf8.hpp
@@ -121,7 +121,7 @@ static OutputIterator wchar_utf8(InputIterator first, InputIterator last, Output
 
 static void utf8_wchar(const std::string &utf8, std::wstring &wide) {
 	wide.clear();
-	utf8_wchar(utf8.begin(), utf8.end(), std::insert_iterator<std::wstring>(wide, wide.end()));
+	detail::utf8_wchar(utf8.begin(), utf8.end(), std::insert_iterator<std::wstring>(wide, wide.end()));
 }
 
 static std::wstring utf8_wchar(const std::string &str) {
@@ -132,7 +132,7 @@ static std::wstring utf8_wchar(const std::string &str) {
 
 static std::string wchar_utf8(const std::wstring &wide, std::string &utf8) {
 	utf8.clear();
-	wchar_utf8(wide.begin(), wide.end(), std::insert_iterator<std::string>(utf8, utf8.end()));
+	detail::wchar_utf8(wide.begin(), wide.end(), std::insert_iterator<std::string>(utf8, utf8.end()));
 }
 
 static std::string wchar_utf8(const std::wstring &str) {
diff --git a/src/file_win.cpp b/src/file_win.cpp
index d6c0a1b04..5f0d2da30 100644
--- a/src/file_win.cpp
+++ b/src/file_win.cpp
@@ -57,15 +57,19 @@ namespace
 
 	void throw_exception(const char* thrower)
 	{
-		char *buffer = 0;
 		int err = GetLastError();
 
-		#ifdef _UNICODE
+		#ifdef UNICODE
+			wchar_t *wbuffer = 0;
 			FormatMessage(
 				FORMAT_MESSAGE_FROM_SYSTEM
 				|FORMAT_MESSAGE_ALLOCATE_BUFFER
-				, 0, err, 0, (LPWSTR)(LPCSTR)&buffer, 0, 0);
+				, 0, err, 0, (LPWCSTR)&wbuffer, 0, 0);
+			std::string tmp_utf8;
+			wchar_utf8(wbuffer, tmp_utf8);
+			char* buffer = tmp_utf8.c_str();
 		#else
+			char* buffer = 0;
 			FormatMessage(
 				FORMAT_MESSAGE_FROM_SYSTEM
 				|FORMAT_MESSAGE_ALLOCATE_BUFFER
@@ -116,7 +120,7 @@ namespace libtorrent
 
 			assert(access_mask & (GENERIC_READ | GENERIC_WRITE));
 
-		#ifdef _UNICODE
+		#ifdef UNICODE
 			std::wstring wfile_name(utf8_wchar(file_name));
 			HANDLE new_handle = CreateFile(
 				(LPCWSTR)wfile_name.c_str()