diff --git a/addons/web/static/src/js/data.js b/addons/web/static/src/js/data.js
index 986c58270ca..d501b1263b1 100644
--- a/addons/web/static/src/js/data.js
+++ b/addons/web/static/src/js/data.js
@@ -253,6 +253,36 @@ instance.web.QueryGroup = instance.web.Class.extend({
 });
 
 instance.web.Model.include({
+    /**
+    new openerp.web.Model([session,] model_name[, context[, domain]])
+
+    @constructs instance.web.Model
+    @extends instance.web.Class
+    
+    @param {openerp.web.Session} [session] The session object used to communicate with
+    the server.
+    @param {String} model_name name of the OpenERP model this object is bound to
+    @param {Object} [context]
+    @param {Array} [domain]
+    */
+    init: function() {
+        var session, model_name, context, domain;
+        var args = _.toArray(arguments);
+        args.reverse();
+        session = args.pop();
+        if (session && ! (session instanceof openerp.web.Session)) {
+            model_name = session;
+            session = null;
+        } else {
+            model_name = args.pop();
+        }
+        context = args.length > 0 ? args.pop() : null;
+        domain = args.length > 0 ? args.pop() : null;
+
+        this._super(session, model_name, context, domain);
+        this._context = context || {};
+        this._domain = domain || [];
+    },
     session: function() {
         if (! this._session)
             return instance.session;
@@ -303,7 +333,7 @@ instance.web.Model.include({
      * @param {String} signal signal to trigger on the workflow
      */
     exec_workflow: function (id, signal) {
-        return instance.session.rpc('/web/dataset/exec_workflow', {
+        return this.session().rpc('/web/dataset/exec_workflow', {
             model: this.name,
             id: id,
             signal: signal
@@ -340,7 +370,7 @@ instance.web.Model.include({
      */
     call_button: function (method, args) {
         instance.web.pyeval.ensure_evaluated(args, {});
-        return instance.session.rpc('/web/dataset/call_button', {
+        return this.session().rpc('/web/dataset/call_button', {
             model: this.name,
             method: method,
             // Should not be necessary anymore. Integrate remote in this?
diff --git a/addons/web/static/src/js/openerpframework.js b/addons/web/static/src/js/openerpframework.js
index 43a45e2d1d2..94149f94dbd 100644
--- a/addons/web/static/src/js/openerpframework.js
+++ b/addons/web/static/src/js/openerpframework.js
@@ -1055,7 +1055,7 @@ openerp.web.Session = openerp.web.Class.extend(openerp.web.PropertiesMixin, {
 
 openerp.web.Model = openerp.web.Class.extend({
     /**
-    new openerp.web.Model([session,] model_name[, context[, domain]])
+    new openerp.web.Model([session,] model_name)
 
     @constructs instance.web.Model
     @extends instance.web.Class
@@ -1067,22 +1067,18 @@ openerp.web.Model = openerp.web.Class.extend({
     @param {Array} [domain]
     */
     init: function () {
-        var session, model_name, context, domain;
+        var session, model_name;
         var args = _.toArray(arguments);
         args.reverse();
         session = args.pop();
-        if (! (session instanceof openerp.web.Session)) {
+        if (session && ! (session instanceof openerp.web.Session)) {
             model_name = session;
             session = null;
         } else {
             model_name = args.pop();
         }
-        context = args.length > 0 ? args.pop() : null;
-        domain = args.length > 0 ? args.pop() : null;
 
         this.name = model_name;
-        this._context = context || {};
-        this._domain = domain || [];
         this._session = session;
     },
     session: function() {