*/
#if defined (HAVE_X_WINDOWS)
-static unsigned char swap_nibble[16] = {
+static const unsigned char swap_nibble[16] = {
0x0, 0x8, 0x4, 0xc, /* 0000 1000 0100 1100 */
0x2, 0xa, 0x6, 0xe, /* 0010 1010 0110 1110 */
0x1, 0x9, 0x5, 0xd, /* 0001 1001 0101 1101 */