[WinAPI] cannot convert from 'LPSTR' to 'LPCWSTR'

#include <windows.h>

int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow )
{
   
   
   
    LPSTR NazwaKlasy = "Klasa Okienka";
   
    WNDCLASSEX wc;
   
    wc.cbSize = sizeof( WNDCLASSEX );
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon( NULL, IDI_APPLICATION );
    wc.hCursor = LoadCursor( NULL, IDC_ARROW );
    wc.hbrBackground =( HBRUSH )( COLOR_WINDOW + 1 );
    wc.lpszMenuName = NULL;
    wc.lpszClassName = NazwaKlasy;
    wc.hIconSm = LoadIcon( NULL, IDI_APPLICATION );
   
    if( !RegisterClassEx( & wc ) )
    {
        MessageBox( NULL, L"Wysoka Komisja odmawia rejestracji tego okna!", L"Niestety...",
        MB_ICONEXCLAMATION | MB_OK );
        return 1;
    }
    return 0;
}