diff --git a/lib/libc/gen/sched_setaffinity.c b/lib/libc/gen/sched_setaffinity.c
index 91ab2a401bda..09e2b9097d5a 100644
--- a/lib/libc/gen/sched_setaffinity.c
+++ b/lib/libc/gen/sched_setaffinity.c
@@ -1,47 +1,52 @@
 /*-
  * Copyright (c) 2021 The FreeBSD Foundation
  *
  * This software were developed by Konstantin Belousov <kib@FreeBSD.org>
  * under sponsorship from the FreeBSD Foundation.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #include <errno.h>
 #include <sched.h>
 #include <string.h>
 
 int
 sched_setaffinity(pid_t pid, size_t cpusetsz, const cpuset_t *cpuset)
 {
 	cpuset_t c;
+	int error;
 
 	if (cpusetsz > sizeof(cpuset_t)) {
 		errno = EINVAL;
 		return (-1);
 	} else {
 		memset(&c, 0, sizeof(c));
 		memcpy(&c, cpuset, cpusetsz);
 	}
-	return (cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID,
-	    pid == 0 ? -1 : pid, sizeof(cpuset_t), &c));
+	error = cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID,
+	    pid == 0 ? -1 : pid, sizeof(cpuset_t), &c);
+	if (error == -1 && errno == EDEADLK)
+		errno = EINVAL;
+
+	return (error);
 }