diff --git a/sbin/reboot/reboot.c b/sbin/reboot/reboot.c
index 7ea4d50eaf7..ac3927cc243 100644
--- a/sbin/reboot/reboot.c
+++ b/sbin/reboot/reboot.c
@@ -130,6 +130,11 @@ write_nextboot(const char *fn, const char *env, bool force)
 	}
 
 	if (zfs) {
+		char *slash;
+
+		if ((slash = strchr(sfs.f_mntfromname, '/')) == NULL)
+			E("Can't find ZFS pool name in %s", sfs.f_mntfromname);
+		*slash = '\0';
 		zfsbootcfg(sfs.f_mntfromname, force);
 	}