diff --git a/lib/express-handlebars.js b/lib/express-handlebars.js
index d6832f3..f5a1451 100644
--- a/lib/express-handlebars.js
+++ b/lib/express-handlebars.js
@@ -23,7 +23,7 @@ function ExpressHandlebars(config) {
     // Config properties with defaults.
     utils.assign(this, {
         handlebars     : Handlebars,
-        extname        : '.handlebars',
+        extname        : '.handlebars', //Deprecated, extname name is defined by the view engine name
         layoutsDir     : undefined, // Default layouts directory is relative to `express settings.view` + `layouts/`
         partialsDir    : undefined, // Default partials directory is relative to `express settings.view` + `partials/`
         defaultLayout  : 'main',