Index: head/bin/ps/print.c
===================================================================
--- head/bin/ps/print.c
+++ head/bin/ps/print.c
@@ -723,11 +723,18 @@
 		break;
 	case RTP_PRIO_NORMAL:
 	/* alias for PRI_TIMESHARE */
-		asprintf(&str, "normal:%u", level - PRI_MIN_TIMESHARE);
+		if (level >= PRI_MIN_TIMESHARE)
+			asprintf(&str, "normal:%u", level - PRI_MIN_TIMESHARE);
+		else
+			asprintf(&str, "kernel:%u", level - PRI_MIN_KERN);
 		break;
 	case RTP_PRIO_IDLE:
 	/* alias for PRI_IDLE */
 		asprintf(&str, "idle:%u", level - PRI_MIN_IDLE);
+		break;
+	case RTP_PRIO_ITHD:
+	/* alias for PRI_ITHD */
+		asprintf(&str, "intr:%u", level - PRI_MIN_ITHD);
 		break;
 	default:
 		asprintf(&str, "%u:%u", class, level);
Index: head/sys/sys/rtprio.h
===================================================================
--- head/sys/sys/rtprio.h
+++ head/sys/sys/rtprio.h
@@ -44,6 +44,7 @@
 
 /* priority types.  Start at 1 to catch uninitialized fields. */
 
+#define RTP_PRIO_ITHD		PRI_ITHD	/* Interrupt thread. */
 #define RTP_PRIO_REALTIME	PRI_REALTIME	/* real time process */
 #define RTP_PRIO_NORMAL		PRI_TIMESHARE	/* time sharing process */
 #define RTP_PRIO_IDLE		PRI_IDLE	/* idle process */