merge doesn't seem to like records

(ns moonrise
  (:require [clojure.core.typed :refer :all]))

(ann-record X [a :- Number])
(defrecord X [a])

(ann x X)
(def x (merge (X. 3) {:z 4}))

Type Error (moonrise:8:8) Polymorphic function clojure.core/merge could not be applied to arguments:
Polymorphic Variables:
	k
	v

Domains:
	nil *
	(clojure.lang.IPersistentMap k v) (clojure.lang.IPersistentMap k v) *
	(Option (clojure.lang.IPersistentMap k v)) *

Arguments:
	moonrise.X (HMap :mandatory {:z (Value 4)} :complete? true)

Ranges:
	nil
	(clojure.lang.IPersistentMap k v)
	(Option (clojure.lang.IPersistentMap k v))

with expected type:
	moonrise.X

in: (clojure.core/merge (new moonrise.X 3) (quote {:z 4}))
in: (def x (clojure.core/merge (new moonrise.X 3) (quote {:z 4})))


Type Checker: Found 1 error