#define pawn_width 32
#define pawn_height 32
-static char pawn_bits[] = {
+static unsigned char pawn_bits[] = {
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xc0,0x01,
0x00,0x00,0x30,0x06,0x00,0x00,0x0c,0x18,0x00,0x00,0x03,0x60,0x00,0x80,0x00,
0x80,0x00,0x80,0x00,0x80,0x01,0x80,0xc0,0x80,0x01,0x40,0xd8,0x03,0x01,0x40,