Ajv issue - formatMinimum $data reference

var Ajv = require('ajv'); ajv = new Ajv(); require('ajv-keywords')(ajv, 'formatMinimum'); var schema = { properties: { start: { type: "string", format: "date" }, end: { type: "string", format: "date", formatMinimum: { $data: "1/start" } } } }; var data = {start: '2013-02-27', end: '2013-02-21'}; var validate = ajv.compile(schema); console.log(validate(data)); console.log(validate.errors);