diff --git a/firefox_addon/lib/hmac.js b/firefox_addon/lib/hmac.js
index a70525d..257c39a 100644
--- a/firefox_addon/lib/hmac.js
+++ b/firefox_addon/lib/hmac.js
@@ -22,19 +22,21 @@ var {Cc, Ci} = require("chrome");
 var hmac = Cc["@mozilla.org/security/hmac;1"]
     .createInstance(Ci.nsICryptoHMAC);
 
-function hmac_init(key) {
-    var keyObject = Cc["@mozilla.org/security/keyobjectfactory;1"]
-                .getService(Ci.nsIKeyObjectFactory)
-                .keyFromString(Ci.nsIKeyObject.HMAC, key);
-    hmac.init(hmac.SHA256, keyObject);
-}
+exports.hmac = {
+    hmac_init : function (key) {
+	var keyObject = Cc["@mozilla.org/security/keyobjectfactory;1"]
+            .getService(Ci.nsIKeyObjectFactory)
+            .keyFromString(Ci.nsIKeyObject.HMAC, key);
+	hmac.init(hmac.SHA256, keyObject);
+    },
 
-function hmac_digest(message) {
-    var data = new Uint8Array(message.length);
-    for(i=0; i<message.length; i++)
-	data[i] = message.charCodeAt(i);
-    hmac.update(data, data.length);
-    res = hmac.finish(false);
-    hmac.reset();
-    return res;
-}
+    hmac_digest : function (message) {
+	var data = new Uint8Array(message.length);
+	for(i=0; i<message.length; i++)
+	    data[i] = message.charCodeAt(i);
+	hmac.update(data, data.length);
+	res = hmac.finish(false);
+	hmac.reset();
+	return res;
+    }
+};
diff --git a/firefox_addon/lib/main.js b/firefox_addon/lib/main.js
index c569dca..35e4307 100644
--- a/firefox_addon/lib/main.js
+++ b/firefox_addon/lib/main.js
@@ -25,9 +25,9 @@ var aes = require("jsaes").aes;
 var parseURI = require("parseuri").parseURI;
 var prefSet = require("sdk/simple-prefs");
 var DEBUG = false;
-var pkdbf2_level = prefSet.prefs.pkdbf2_level;
+var pkdbf2_level = getPref("pkdbf2_level");
 var protocol_version = 3;
-SERVER = { OK : 0, FAILED : 1, RESTART_REQUEST : 2};
+SERVER = {OK : 0, FAILED : 1, RESTART_REQUEST : 2};
 
 // http://stackoverflow.com/questions/3745666/how-to-convert-from-hex-to-ascii-in-javascript
 function hex2a(hex) {
@@ -63,6 +63,16 @@ function notify(text, data)
     });
 }
 
+function getPref(key)
+{
+    return prefSet.prefs[key];
+}
+
+function setPref(key, value)
+{
+    prefSet.prefs[key] = value;
+}
+
 function generate_request(domain, login, mkey)
 {
     var v = "@@" + domain + ";" + login;
@@ -171,7 +181,7 @@ function ask_server(form, field, logins, domain, wdomain, mkey, salt, submit)
 		{
 		    debug("New pkdbf2 level " + server_pkdbf2_level);
 		    pkdbf2_level = server_pkdbf2_level;
-		    prefSet.prefs.pkdbf2_level = server_pkdbf2_level;
+		    setPref("pkdbf2_level", pkdbf2_level);
 		    ret = SERVER.RESTART_REQUEST;
 		}
 		break;
@@ -228,8 +238,8 @@ function ask_server(form, field, logins, domain, wdomain, mkey, salt, submit)
 	notify("Error",
 	       "Error");
     }, false);
-    debug("connect to " + prefSet.prefs.account_url);
-    gPassRequest.open("POST", prefSet.prefs.account_url, true);
+    debug("connect to " + getPref("account_url"));
+    gPassRequest.open("POST", getPref("account_url"), true);
     gPassRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
     gPassRequest.send(keys);
 
@@ -268,7 +278,7 @@ function on_sumbit(e)
     domain = domain["host"];
     var wdomain = wildcard_domain(domain);
 
-    var salt = parseURI.parseUri(prefSet.prefs.account_url);
+    var salt = parseURI.parseUri(getPref("account_url"));
     salt = salt["host"] + salt["path"];
 
     debug("salt " + salt);
diff --git a/firefox_addon/lib/pkdbf2.js b/firefox_addon/lib/pkdbf2.js
index b45d011..cd7e96c 100644
--- a/firefox_addon/lib/pkdbf2.js
+++ b/firefox_addon/lib/pkdbf2.js
@@ -17,7 +17,7 @@
   along with gPass.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-require("hmac.js");
+var hmac = require("hmac.js").hmac;
 
 exports.pkdbf2 = {
     
@@ -28,10 +28,10 @@ exports.pkdbf2 = {
 	var temp_res = "";
 	var temp_res2 = "";
 	    
-	hmac_init(password);
+	hmac.hmac_init(password);
 	for (i=1; result.length < outlen; i++)
 	{
-	    temp = hmac_digest(salt + 
+	    temp = hmac.hmac_digest(salt + 
 	    		       String.fromCharCode((i & 0xff000000) >> 24) +
 	    		       String.fromCharCode((i & 0x00ff0000) >> 16) +
 	    		       String.fromCharCode((i & 0x0000ff00) >>  8) +
@@ -41,7 +41,7 @@ exports.pkdbf2 = {
 	    
 	    for(a=1; a<iterations; a++)
 	    {
-		temp2 = hmac_digest(temp);
+		temp2 = hmac.hmac_digest(temp);
 		temp_res2 = "";
 		for(b = 0; b<temp_res.length; b++)
 		    temp_res2 += String.fromCharCode(temp_res.charCodeAt(b) ^ temp2.charCodeAt(b));