--- ckcasc.h

+++ ckcasc.h

@@ -42,7 +42,7 @@

 #define SYN   22        /* SYN, Ctrl-V */

 #define ETB   23        /* Ctrl-W */

 #define CAN   24        /* CAN, Ctrl-X */

-#define EM    25        /* Ctrl-Y */

+#define _EM   25        /* Ctrl-Y */

 #define SUB   26        /* SUB Ctrl-Z */

 #define ESC   27        /* Escape Ctrl-[ */

 #define XFS   28        /* Field Separator,  Ctrl-Backslash */