--- sys/kern/kern_jail.c
+++ sys/kern/kern_jail.c
@@ -1588,7 +1588,7 @@
 		/* Give a default name of the jid. */
 		if (name[0] == '\0')
 			snprintf(name = numbuf, sizeof(numbuf), "%d", jid);
-		else if (*namelc == '0' || (strtoul(namelc, &p, 10) != jid &&
+		else if ((namelc[0] == '0' && namelc[1] == '\0') || (strtoul(namelc, &p, 10) != jid &&
 		    *p == '\0')) {
 			error = EINVAL;
 			vfs_opterror(opts,