#define bigblank_width 32
#define bigblank_height 32
-static char bigblank_bits[] = {
+static unsigned char bigblank_bits[] = {
0x00,0x00,0x00,0x00,0x00,0xe0,0x03,0x00,0x00,0x18,0x0c,0x00,0x00,0x06,0x30,
0x00,0x80,0x01,0xc0,0x00,0x40,0x00,0x00,0x01,0x40,0x00,0x00,0x03,0x40,0x00,
0x00,0x03,0x40,0x00,0x00,0x03,0x20,0x00,0x00,0x02,0x20,0x00,0x00,0x06,0x20,