diff --git a/src/lib-storage/mail-namespace.c b/src/lib-storage/mail-namespace.c
index 88c0ce606fd..330bbbf5600 100644
--- a/src/lib-storage/mail-namespace.c
+++ b/src/lib-storage/mail-namespace.c
@@ -735,7 +735,7 @@ mail_namespace_find_unsubscribable(struct mail_namespace *namespaces,
 struct mail_namespace *
 mail_namespace_find_inbox(struct mail_namespace *namespaces)
 {
-	while ((namespaces->flags & NAMESPACE_FLAG_INBOX_USER) == 0)
+	while (namespaces!=NULL && (namespaces->flags & NAMESPACE_FLAG_INBOX_USER) == 0)
 		namespaces = namespaces->next;
 	return namespaces;
 }