diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -3085,8 +3085,7 @@
 	FOREACH_PROC_IN_SYSTEM(p) {
 		PROC_LOCK(p);
 		if (p->p_state != PRS_NEW && p->p_ucred != NULL) {
-			for (ppr = p->p_ucred->cr_prison;
-			    ppr != &prison0;
+			for (ppr = p->p_ucred->cr_prison; ppr != NULL;
 			    ppr = ppr->pr_parent) {
 				if (ppr == pr) {
 					cb(p, cbarg);