Deep merging configs of host app and addon in ember

Normally config/environment.js files of host application and addon are merged. But top level only.

For example:

//addon config/environment.js    
module.exports = function() {
    return {
        addonRootVar: 'exist after merge'
        APP: {
            addonDeepVar: 'doesn\'t exist in resulting config'
        }     
    }
}

//host app config/environment.js
module.exports = function() {
return {
    hostRootVar: 'exist after merge'
        APP: {
            hostDeepVar: 'whole APP property will be overwritten :('
        }
    }
}

Is is possible to deepMerge configs?(to have both addonDeepVar and hostDeepVar present in resulting config) If yes – How?