diff --git a/src/RS232_win.c b/src/RS232_win.c
--- a/src/RS232_win.c
+++ b/src/RS232_win.c
@@ -119,11 +119,12 @@ rs232port_t rs232open(char* psPortName)
 {
         rs232port_t fd;
         /* Char to Wchar conversion*/
-        int len  = strlen(psPortName),convlen;
-        wchar_t *wcstr = (wchar_t *)malloc((len*sizeof(wchar_t)) + 10);
-        mbstowcs_s(&convlen,wcstr,len, psPortName,len);
+        int neededSize = MultiByteToWideChar(CP_ACP, 0, psPortName, -1, 0, 0);
+        wchar_t* wcstr = new wchar_t[neededSize];
+        MultiByteToWideChar(CP_ACP, 0, charString, -1, wcstr, neededSize);
         fd = (rs232port_t)CreateFile(wcstr,GENERIC_READ | GENERIC_WRITE,0,0,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,0);
-        #ifdef RS232_debug
+        delete wcstr;
+#ifdef RS232_debug
 		if(fd==(rs232port_t)INVALID_HANDLE_VALUE)
 		{
 			printf("can't open Port\n");