diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index a1734e1..b42a172 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -953,8 +953,9 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 		VOP_UNLOCK(root, 0);
 		if (fullpath_disabled) {
 			/* Leave room for a real-root full pathname. */
-			if (len + (path[0] == '/' && strcmp(mypr->pr_path, "/")
-			    ? strlen(mypr->pr_path) : 0) > MAXPATHLEN) {
+			if (len + (path != NULL && path[0] == '/' &&
+			    strcmp(mypr->pr_path, "/") ?
+			    strlen(mypr->pr_path) : 0) > MAXPATHLEN) {
 				error = ENAMETOOLONG;
 				vrele(root);
 				goto done_free;