diff --git a/firefox_addon/lib/pkdbf2.js b/firefox_addon/lib/pkdbf2.js
index cd7e96c..a7a9363 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/>.
 */
 
-var hmac = require("hmac.js").hmac;
+var hmac = require("hmac").hmac;
 
 exports.pkdbf2 = {