-#define PSIOAUTOREFRESH _IO(p, 0) /* auto refresh */
-#define PSIOSINGLEREFRESH _IO(p, 1) /* single refresh */
-#define PSIOAUTOMAP _IO(p, 2) /* auto map */
-#define PSIOSINGLEMAP _IO(p, 3) /* single map */
-#define PSIODOUBLEBUFFER _IO(p, 4) /* double buffer */
-#define PSIOSINGLEBUFFER _IO(p, 5) /* single buffer */
-#define PSIOWAITREFRESH _IO(p, 6) /* await refresh */
-#define PSIOWAITMAP _IO(p, 7) /* await map */
-#define PSIOWAITHIT _IO(p, 8) /* await hit */
-#define PSIOSTOPREFRESH _IO(p, 9) /* stop refresh */
-#define PSIOSTOPMAP _IO(p,10) /* stop map */
-#define PSIOGETADDR _IOR(p,11, int) /* get Unibus address */
-#define PSIOTIMEREFRESH _IO(p,12) /* time refresh */
+#define PSIOAUTOREFRESH _IO('p', 0) /* auto refresh */
+#define PSIOSINGLEREFRESH _IO('p', 1) /* single refresh */
+#define PSIOAUTOMAP _IO('p', 2) /* auto map */
+#define PSIOSINGLEMAP _IO('p', 3) /* single map */
+#define PSIODOUBLEBUFFER _IO('p', 4) /* double buffer */
+#define PSIOSINGLEBUFFER _IO('p', 5) /* single buffer */
+#define PSIOWAITREFRESH _IO('p', 6) /* await refresh */
+#define PSIOWAITMAP _IO('p', 7) /* await map */
+#define PSIOWAITHIT _IO('p', 8) /* await hit */
+#define PSIOSTOPREFRESH _IO('p', 9) /* stop refresh */
+#define PSIOSTOPMAP _IO('p',10) /* stop map */
+#define PSIOGETADDR _IOR('p',11, int) /* get Unibus address */
+#define PSIOTIMEREFRESH _IO('p',12) /* time refresh */