diff --git a/lib/certificate.js b/lib/certificate.js
index 4fbe6ab..07b04af 100644
--- a/lib/certificate.js
+++ b/lib/certificate.js
@@ -6,9 +6,7 @@ var assert = require('assert-plus');
 var algs = require('./algs');
 var crypto = require('crypto');
 var Fingerprint = require('./fingerprint');
-var Signature = require('./signature');
 var errs = require('./errors');
-var util = require('util');
 var utils = require('./utils');
 var Key = require('./key');
 var PrivateKey = require('./private-key');