diff --git a/lib/acme-client.js b/lib/acme-client.js
index cb9a320..5dd199f 100644
--- a/lib/acme-client.js
+++ b/lib/acme-client.js
@@ -14,7 +14,7 @@ module.exports.create = function (deps) {
   var generateSignature=deps.RSA.signJws;
 
   function Acme(keypair) {
-    this.keypair;
+    this.keypair = keypair;
     this.nonces=[];
   }