#define knightR_width 32
#define knightR_height 32
-static char knightR_bits[] = {
+static unsigned char knightR_bits[] = {
0xfc,0xff,0xff,0x1f,0x04,0x00,0x00,0x30,0x04,0x00,0x00,0x30,0x04,0x4c,0x15,
0x30,0x04,0x06,0x00,0x30,0x08,0xfe,0x0f,0x18,0x08,0xc0,0x0c,0x18,0x08,0xf8,
0x0f,0x18,0x08,0xc0,0x0c,0x18,0x10,0xf8,0x0f,0x0c,0x10,0xc0,0x0c,0x0c,0x10,