self.build is not a function while UserSchema.register()

[f1nnix]

Error:

TypeError: self.build is not a function

Stack:

TypeError: self.build is not a function
    at UserSchema.register (/src/node_modules/passport-local-sequelize/lib/passport-local-sequelize.js:182:25)
    at /src/server/test/seed-users.js:11:12

The problem is caused by:

UserSchema.register = function (user, password, cb) {
        var self = this,
            fields = {};

        if (user instanceof UserSchema.Instance) {
            // Do nothing
        } else if (_.isString(user)) {
            // Create an instance of this in case user is passed as username
            fields[options.usernameField] = user;

            user = self.build(fields);
        } else if (_.isObject(user)) {
            // Create an instance if user is passed as fields
            user = self.build(user); // <===== THIS LINE
        }

Env:

root@c16383fbfd19:/src# node -v
v5.1.0

Babel-config:

{
  "optional": ["es7.decorators", "es7.classProperties", "es7.objectRestSpread"]
}

with require('babel/register')({});

Thanks.