-#define MTIOCTOP _IOW(m, 1, struct mtop) /* do a mag tape op */
-#define MTIOCGET _IOR(m, 2, struct mtget) /* get tape status */
-#define MTIOCIEOT _IO(m, 3) /* ignore EOT error */
-#define MTIOCEEOT _IO(m, 4) /* enable EOT error */
+#define MTIOCTOP _IOW('m', 1, struct mtop) /* do a mag tape op */
+#define MTIOCGET _IOR('m', 2, struct mtget) /* get tape status */
+#define MTIOCIEOT _IO('m', 3) /* ignore EOT error */
+#define MTIOCEEOT _IO('m', 4) /* enable EOT error */