diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 9e363e4..0855f77 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -246,6 +246,12 @@
 	umode_t mode = 0;
 	int not_equiv = 0;
 
+	/*
+	 * A null ACL can always be presented as mode bits.
+	 */
+	if (!acl)
+		return 0;
+
 	FOREACH_ACL_ENTRY(pa, acl, pe) {
 		switch (pa->e_tag) {
 			case ACL_USER_OBJ: