diff --git a/sys/kern/ksched.c b/sys/kern/ksched.c
--- a/sys/kern/ksched.c
+++ b/sys/kern/ksched.c
@@ -186,7 +186,7 @@
 			    RTP_PRIO_REALTIME;
 			rtp_to_pri(&rtp, td);
 		} else {
-			e = EPERM;
+			e = EINVAL;
 		}
 		break;
 	case SCHED_OTHER: