om.next/cljs.spec interaction warning

compilation

λ lein cljsbuild once prod
Compiling ClojureScript...
Compiling "out/main.js" from ["src"]...
Sep 26, 2016 7:03:38 PM com.google.javascript.jscomp.LoggerErrorManager println
WARNING: /Users/grzm/Documents/dev/om-namespace/out/cljs/analyzer.js:4740: WARNING - incomplete alias created for namespace cljs.spec
var mchk = (function (){var and__6935__auto__ = cljs.spec;
                                                ^

Sep 26, 2016 7:03:38 PM com.google.javascript.jscomp.LoggerErrorManager printSummary
WARNING: 0 error(s), 1 warning(s)
Successfully compiled "out/main.js" in 39.895 seconds.

core.cljs

(ns om-ns.core
  (:require
   [cljs.spec]
   [om.next]))

project.clj

(defproject om-ns "0.0.1-SNAPSHOT"
  :dependencies [[org.clojure/clojure "1.9.0-alpha12"]
                 [org.clojure/clojurescript "1.9.229"]
                 [org.omcljs/om "1.0.0-alpha46"]]
  :plugins [[lein-cljsbuild "1.1.4"]]
  :source-paths ["src"]
  :cljsbuild {:builds [{:id "prod"
                        :source-paths ["src"]
                        :compiler {:optimizations :advanced
                                   :output-to "out/main.js"
                                   :output-dir "out"}}]})