diff --git a/.eslintrc b/.eslintrc
deleted file mode 100644
index a1b4aa0..0000000
--- a/.eslintrc
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-  "extends": [
-    "eslint-config-airbnb-base",
-    "eslint-config-airbnb-base/rules/strict"
-  ],
-  "rules": {
-    "no-param-reassign": 0,
-    "object-shorthand": 0,
-    "strict": 0,
-    "consistent-return": 0
-  }
-}
diff --git a/.eslintrc.yml b/.eslintrc.yml
new file mode 100644
index 0000000..ad5b831
--- /dev/null
+++ b/.eslintrc.yml
@@ -0,0 +1,22 @@
+# Support ES2016 features
+parser: babel-eslint
+
+extends: standard
+
+plugins: [
+  "babel"
+]
+
+rules:
+  arrow-parens: 0
+  babel/arrow-parens: [2, "as-needed"]
+  comma-dangle: [2, "always-multiline"]
+  eqeqeq: 0
+  no-return-assign: 0 # fails for arrow functions
+  no-var: 2
+  semi: [2, always]
+  space-before-function-paren: [2, never]
+  yoda: 0
+  arrow-spacing: 2
+  dot-location: [2, "property"]
+  prefer-arrow-callback: 2
diff --git a/index.js b/index.js
index 986d93c..30831f9 100644
--- a/index.js
+++ b/index.js
@@ -7,16 +7,22 @@ const debug = require('debug')('koa-simple-ratelimit');
 const ms = require('ms');
 
 function find(db, p) {
-  return new Promise((resolve) => {
+  return new Promise((resolve, reject) => {
     db.get(p, (err, reply) => {
+      if (err) {
+        reject(err);
+      }
       resolve(reply);
     });
   });
 }
 
 function pttl(db, p) {
-  return new Promise((resolve) => {
+  return new Promise((resolve, reject) => {
     db.pttl(p, (err, reply) => {
+      if (err) {
+        reject(err);
+      }
       resolve(reply);
     });
   });
@@ -46,7 +52,7 @@ function ratelimit(opts) {
   opts.headers.reset = opts.headers.reset || 'X-RateLimit-Reset';
   opts.headers.total = opts.headers.total || 'X-RateLimit-Limit';
 
-  return function ratelimiter(ctx, next) {
+  return async function ratelimiter(ctx, next) {
     const id = opts.id ? opts.id(ctx) : ctx.ip;
 
     if (id === false) {
@@ -63,53 +69,50 @@ function ratelimit(opts) {
     }
 
     const name = `limit:${id}:count`;
-    return find(opts.db, name).then((cur) => {
-      const n = Math.floor(cur);
-      let t = Date.now();
-      t += opts.duration || 3600000;
-      t = new Date(t).getTime() / 1000 || 0;
+    const cur = await find(opts.db, name);
+    const n = Math.floor(cur);
+    let t = Date.now();
+    t += opts.duration || 3600000;
+    t = new Date(t).getTime() / 1000 || 0;
 
-      const headers = {};
-      headers[opts.headers.remaining] = opts.max - 1;
-      headers[opts.headers.reset] = t;
-      headers[opts.headers.total] = opts.max;
-      ctx.set(headers);
+    const headers = {};
+    headers[opts.headers.remaining] = opts.max - 1;
+    headers[opts.headers.reset] = t;
+    headers[opts.headers.total] = opts.max;
+    ctx.set(headers);
 
-      // not existing in redis
-      if (cur === null) {
-        debug('remaining %s/%s %s', opts.max - 1, opts.max, id);
-        opts.db.set(name, opts.max - 1, 'PX', opts.duration || 3600000, 'NX');
-        return next();
-      }
+    // not existing in redis
+    if (cur === null) {
+      debug('remaining %s/%s %s', opts.max - 1, opts.max, id);
+      opts.db.set(name, opts.max - 1, 'PX', opts.duration || 3600000, 'NX');
+      return next();
+    }
 
-      return pttl(opts.db, name).then((expires) => {
-        if (n - 1 >= 0) {
-          // existing in redis
-          opts.db.decr(name);
-          debug('remaining %s/%s %s', n - 1, opts.max, id);
-          headers[opts.headers.remaining] = n - 1;
-          ctx.set(headers);
-          return next();
-        }
-        if (expires < 0) {
-          debug(`${name} is stuck. Resetting.`);
-          debug('remaining %s/%s %s', opts.max - 1, opts.max, id);
-          opts.db.set(name, opts.max - 1, 'PX', opts.duration || 3600000, 'NX');
-          return next();
-        }
-        // user maxed
-        headers['Retry-After'] = t;
-        headers[opts.headers.remaining] = n;
-        ctx.set(headers);
-        ctx.status = 429;
-        const retryTime = ms(expires, { long: true });
-        ctx.body = `Rate limit exceeded, retry in ${retryTime}`;
-        if (opts.throw) {
-          ctx.throw(ctx.status, ctx.body, { headers: headers });
-        }
-        return;
-      });
-    });
+    const expires = await pttl(opts.db, name);
+    if (n - 1 >= 0) {
+      // existing in redis
+      opts.db.decr(name);
+      debug('remaining %s/%s %s', n - 1, opts.max, id);
+      headers[opts.headers.remaining] = n - 1;
+      ctx.set(headers);
+      return next();
+    }
+    if (expires < 0) {
+      debug(`${name} is stuck. Resetting.`);
+      debug('remaining %s/%s %s', opts.max - 1, opts.max, id);
+      opts.db.set(name, opts.max - 1, 'PX', opts.duration || 3600000, 'NX');
+      return next();
+    }
+    // user maxed
+    headers['Retry-After'] = t;
+    headers[opts.headers.remaining] = n;
+    ctx.set(headers);
+    ctx.status = 429;
+    const retryTime = ms(expires, { long: true });
+    ctx.body = `Rate limit exceeded, retry in ${retryTime}`;
+    if (opts.throw) {
+      ctx.throw(ctx.status, ctx.body, { headers: headers });
+    }
   };
 }
 
diff --git a/package.json b/package.json
index 70a9dcb..4ccde54 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "koa-simple-ratelimit",
   "description": "Simple Rate limiter middleware for koa v2",
-  "version": "2.1.4",
+  "version": "2.2.0",
   "scripts": {
     "test": "NODE_ENV=test node_modules/mocha/bin/mocha --reporter spec",
     "lint": "eslint index.js test; exit 0",
@@ -13,14 +13,18 @@
     "ms": "^0.7.2"
   },
   "devDependencies": {
+    "babel-eslint": "^7.1.1",
+    "chai": "^3.5.0",
     "eslint": "^3.17.1",
-    "eslint-config-airbnb-base": "^11.1.1",
+    "eslint-config-standard": "^7.0.1",
+    "eslint-plugin-babel": "^4.1.1",
     "eslint-plugin-import": "^2.2.0",
+    "eslint-plugin-promise": "^3.5.0",
+    "eslint-plugin-standard": "^2.1.1",
     "koa": "^2.1.0",
     "mocha": "^3.2.0",
     "nyc": "^10.1.2",
     "redis": "^2.6.5",
-    "should": "^11.2.0",
     "supertest": "^3.0.0"
   },
   "nyc": {
diff --git a/test/.eslintrc b/test/.eslintrc
index 3a4690f..cda2f26 100644
--- a/test/.eslintrc
+++ b/test/.eslintrc
@@ -1,12 +1,5 @@
-{
-  "extends": "../.eslintrc",
-  "env": {
-    "mocha": true
-  },
-  "rules": {
-    "prefer-arrow-callback": 0,
-    "import/no-extraneous-dependencies": ["error", { "devDependencies": true }],
-    "func-names": 0,
-    "no-unused-vars": 0
-  }
-}
\ No newline at end of file
+env:
+  mocha: true
+
+rules:
+  space-before-blocks: [2, {functions: never, keywords: always}]
diff --git a/test/ratelimit.js b/test/ratelimit.js
index 79e157a..fb705b7 100644
--- a/test/ratelimit.js
+++ b/test/ratelimit.js
@@ -1,8 +1,8 @@
 'use strict';
 
+const expect = require('chai').expect;
 const Koa = require('koa');
 const request = require('supertest');
-const should = require('should');
 const redis = require('redis');
 
 const ratelimit = require('..');
@@ -15,6 +15,9 @@ describe('ratelimit middleware', () => {
 
   before((done) => {
     db.keys('limit:*', (err, rows) => {
+      if (err) {
+        throw new Error(err);
+      }
       rows.forEach(n => db.del(n));
     });
 
@@ -26,7 +29,7 @@ describe('ratelimit middleware', () => {
     let app;
 
     const routeHitOnlyOnce = () => {
-      guard.should.be.equal(1);
+      expect(guard).to.eq(1);
     };
 
     beforeEach((done) => {
@@ -79,10 +82,10 @@ describe('ratelimit middleware', () => {
     let app;
 
     const routeHitOnlyOnce = () => {
-      guard.should.be.equal(1);
+      expect(guard).to.eq(1);
     };
     const routeHitTwice = () => {
-      guard.should.be.equal(2);
+      expect(guard).to.eq(2);
     };
 
     beforeEach((done) => {
@@ -142,7 +145,7 @@ describe('ratelimit middleware', () => {
     let app;
 
     const routeHitOnlyOnce = () => {
-      guard.should.be.equal(1);
+      expect(guard).to.eq(1);
     };
 
     beforeEach((done) => {
@@ -169,6 +172,7 @@ describe('ratelimit middleware', () => {
       request(app.listen())
         .get('/')
         .expect('X-RateLimit-Remaining', '0')
+        .expect(routeHitOnlyOnce)
         .expect(200)
         .end(done);
     });
@@ -179,7 +183,7 @@ describe('ratelimit middleware', () => {
     let app;
 
     const routeHitOnlyOnce = () => {
-      guard.should.be.equal(1);
+      expect(guard).to.eq(1);
     };
 
     beforeEach((done) => {
@@ -239,12 +243,12 @@ describe('ratelimit middleware', () => {
         .get('/')
         .set('foo', 'bar')
         .expect((res) => {
-          res.header['x-ratelimit-remaining'].should.equal('0');
+          expect(res.header['x-ratelimit-remaining']).to.eq('0');
         })
         .end(done);
     });
 
-    it('should not limit if `id` returns `false`', (done) => {
+    it('should not limit if `id` returns `false`', () => {
       const app = new Koa();
 
       app.use(ratelimit({
@@ -254,12 +258,9 @@ describe('ratelimit middleware', () => {
         max: 5,
       }));
 
-      request(app.listen())
+      return request(app.listen())
         .get('/')
-        .expect((res) => {
-          res.header.should.not.have.property('x-ratelimit-remaining');
-        })
-        .end(done);
+        .expect((res) => expect(res.header['x-ratelimit-remaining']).to.not.exist);
     });
 
     it('should limit using the `id` value', (done) => {
diff --git a/yarn.lock b/yarn.lock
index ebf4773..90de9af 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -106,6 +106,10 @@ arrify@^1.0.0, arrify@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/arrify/-/arrify-1.0.1.tgz#898508da2226f380df904728456849c1501a4b0d"
 
+assertion-error@^1.0.1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/assertion-error/-/assertion-error-1.0.2.tgz#13ca515d86206da0bac66e834dd397d87581094c"
+
 async@^1.4.0, async@^1.4.2:
   version "1.5.2"
   resolved "https://registry.yarnpkg.com/async/-/async-1.5.2.tgz#ec6a61ae56480c0c3cb241c95618e20892f9672a"
@@ -122,6 +126,16 @@ babel-code-frame@^6.16.0, babel-code-frame@^6.22.0:
     esutils "^2.0.2"
     js-tokens "^3.0.0"
 
+babel-eslint@^7.1.1:
+  version "7.1.1"
+  resolved "https://registry.yarnpkg.com/babel-eslint/-/babel-eslint-7.1.1.tgz#8a6a884f085aa7060af69cfc77341c2f99370fb2"
+  dependencies:
+    babel-code-frame "^6.16.0"
+    babel-traverse "^6.15.0"
+    babel-types "^6.15.0"
+    babylon "^6.13.0"
+    lodash.pickby "^4.6.0"
+
 babel-generator@^6.18.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-generator/-/babel-generator-6.23.0.tgz#6b8edab956ef3116f79d8c84c5a3c05f32a74bc5"
@@ -158,7 +172,7 @@ babel-template@^6.16.0:
     babylon "^6.11.0"
     lodash "^4.2.0"
 
-babel-traverse@^6.18.0, babel-traverse@^6.23.0:
+babel-traverse@^6.15.0, babel-traverse@^6.18.0, babel-traverse@^6.23.0:
   version "6.23.1"
   resolved "https://registry.yarnpkg.com/babel-traverse/-/babel-traverse-6.23.1.tgz#d3cb59010ecd06a97d81310065f966b699e14f48"
   dependencies:
@@ -172,7 +186,7 @@ babel-traverse@^6.18.0, babel-traverse@^6.23.0:
     invariant "^2.2.0"
     lodash "^4.2.0"
 
-babel-types@^6.18.0, babel-types@^6.23.0:
+babel-types@^6.15.0, babel-types@^6.18.0, babel-types@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-types/-/babel-types-6.23.0.tgz#bb17179d7538bad38cd0c9e115d340f77e7e9acf"
   dependencies:
@@ -249,6 +263,14 @@ center-align@^0.1.1:
     align-text "^0.1.3"
     lazy-cache "^1.0.3"
 
+chai@^3.5.0:
+  version "3.5.0"
+  resolved "https://registry.yarnpkg.com/chai/-/chai-3.5.0.tgz#4d02637b067fe958bdbfdd3a40ec56fef7373247"
+  dependencies:
+    assertion-error "^1.0.1"
+    deep-eql "^0.1.3"
+    type-detect "^1.0.0"
+
 chalk@^1.0.0, chalk@^1.1.0, chalk@^1.1.1, chalk@^1.1.3:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/chalk/-/chalk-1.1.3.tgz#a8115c55e4a702fe4d150abd3872822a7e09fc98"
@@ -397,6 +419,12 @@ decamelize@^1.0.0, decamelize@^1.1.1:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/decamelize/-/decamelize-1.2.0.tgz#f6534d15148269b20352e7bee26f501f9a191290"
 
+deep-eql@^0.1.3:
+  version "0.1.3"
+  resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-0.1.3.tgz#ef558acab8de25206cd713906d74e56930eb69f2"
+  dependencies:
+    type-detect "0.1.1"
+
 deep-equal@~1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/deep-equal/-/deep-equal-1.0.1.tgz#f5d260292b660e084eff4cdbc9f08ad3247448b5"
@@ -543,9 +571,9 @@ escope@^3.6.0:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
-eslint-config-airbnb-base@^11.1.1:
-  version "11.1.1"
-  resolved "https://registry.yarnpkg.com/eslint-config-airbnb-base/-/eslint-config-airbnb-base-11.1.1.tgz#61e9e89e4eb89f474f6913ac817be9fbb59063e0"
+eslint-config-standard@^7.0.1:
+  version "7.0.1"
+  resolved "https://registry.yarnpkg.com/eslint-config-standard/-/eslint-config-standard-7.0.1.tgz#6cec96084de9ac862c33ccb953d13a7c59872342"
 
 eslint-import-resolver-node@^0.2.0:
   version "0.2.3"
@@ -562,6 +590,10 @@ eslint-module-utils@^2.0.0:
     debug "2.2.0"
     pkg-dir "^1.0.0"
 
+eslint-plugin-babel@^4.1.1:
+  version "4.1.1"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-babel/-/eslint-plugin-babel-4.1.1.tgz#ef285c87039b67beb3bbd227f5b0eed4fb376b87"
+
 eslint-plugin-import@^2.2.0:
   version "2.2.0"
   resolved "https://registry.yarnpkg.com/eslint-plugin-import/-/eslint-plugin-import-2.2.0.tgz#72ba306fad305d67c4816348a4699a4229ac8b4e"
@@ -577,6 +609,14 @@ eslint-plugin-import@^2.2.0:
     minimatch "^3.0.3"
     pkg-up "^1.0.0"
 
+eslint-plugin-promise@^3.5.0:
+  version "3.5.0"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-promise/-/eslint-plugin-promise-3.5.0.tgz#78fbb6ffe047201627569e85a6c5373af2a68fca"
+
+eslint-plugin-standard@^2.1.1:
+  version "2.1.1"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-standard/-/eslint-plugin-standard-2.1.1.tgz#97960b1537e1718bb633877d0a650050effff3b0"
+
 eslint@^3.17.1:
   version "3.17.1"
   resolved "https://registry.yarnpkg.com/eslint/-/eslint-3.17.1.tgz#b80ae12d9c406d858406fccda627afce33ea10ea"
@@ -1300,6 +1340,10 @@ lodash.keys@^3.0.0:
     lodash.isarguments "^3.0.0"
     lodash.isarray "^3.0.0"
 
+lodash.pickby@^4.6.0:
+  version "4.6.0"
+  resolved "https://registry.yarnpkg.com/lodash.pickby/-/lodash.pickby-4.6.0.tgz#7dea21d8c18d7703a27c704c15d3b84a67e33aff"
+
 lodash@^4.0.0, lodash@^4.2.0, lodash@^4.3.0:
   version "4.17.4"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.4.tgz#78203a4d1c328ae1d86dca6460e369b57f4055ae"
@@ -1803,44 +1847,6 @@ shelljs@^0.7.5:
     interpret "^1.0.0"
     rechoir "^0.6.2"
 
-should-equal@^1.0.0:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/should-equal/-/should-equal-1.0.1.tgz#0b6e9516f2601a9fb0bb2dcc369afa1c7e200af7"
-  dependencies:
-    should-type "^1.0.0"
-
-should-format@^3.0.2:
-  version "3.0.3"
-  resolved "https://registry.yarnpkg.com/should-format/-/should-format-3.0.3.tgz#9bfc8f74fa39205c53d38c34d717303e277124f1"
-  dependencies:
-    should-type "^1.3.0"
-    should-type-adaptors "^1.0.1"
-
-should-type-adaptors@^1.0.1:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/should-type-adaptors/-/should-type-adaptors-1.0.1.tgz#efe5553cdf68cff66e5c5f51b712dc351c77beaa"
-  dependencies:
-    should-type "^1.3.0"
-    should-util "^1.0.0"
-
-should-type@^1.0.0, should-type@^1.3.0, should-type@^1.4.0:
-  version "1.4.0"
-  resolved "https://registry.yarnpkg.com/should-type/-/should-type-1.4.0.tgz#0756d8ce846dfd09843a6947719dfa0d4cff5cf3"
-
-should-util@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/should-util/-/should-util-1.0.0.tgz#c98cda374aa6b190df8ba87c9889c2b4db620063"
-
-should@^11.2.0:
-  version "11.2.0"
-  resolved "https://registry.yarnpkg.com/should/-/should-11.2.0.tgz#7afca3182c234781d786d2278a87805b5ecf0409"
-  dependencies:
-    should-equal "^1.0.0"
-    should-format "^3.0.2"
-    should-type "^1.4.0"
-    should-type-adaptors "^1.0.1"
-    should-util "^1.0.0"
-
 signal-exit@^2.0.0:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/signal-exit/-/signal-exit-2.1.2.tgz#375879b1f92ebc3b334480d038dc546a6d558564"
@@ -2018,6 +2024,14 @@ type-check@~0.3.2:
   dependencies:
     prelude-ls "~1.1.2"
 
+type-detect@0.1.1:
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-0.1.1.tgz#0ba5ec2a885640e470ea4e8505971900dac58822"
+
+type-detect@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-1.0.0.tgz#762217cc06db258ec48908a1298e8b95121e8ea2"
+
 type-is@^1.5.5:
   version "1.6.14"
   resolved "https://registry.yarnpkg.com/type-is/-/type-is-1.6.14.tgz#e219639c17ded1ca0789092dd54a03826b817cb2"