diff --git a/include/proto/auth.h b/include/proto/auth.h
index 8c060b5..c7b2abc 100644
--- a/include/proto/auth.h
+++ b/include/proto/auth.h
@@ -22,6 +22,7 @@
 unsigned int auth_resolve_groups(struct userlist *l, char *groups);
 void userlist_free(struct userlist *ul);
 int acl_match_auth(struct acl_test *test, struct acl_pattern *pattern);
+int check_user(struct userlist *ul, unsigned int group_mask, const char *user, const char *pass);
 
 #endif /* _PROTO_AUTH_H */