diff --git a/src/collection.js b/src/collection.js
index ae1c6e99e..8827d3265 100644
--- a/src/collection.js
+++ b/src/collection.js
@@ -112,6 +112,8 @@ Collection.prototype.remove = function (ids) {
 		delete this.models[id];
 	}, this);
 
+	this.emit('remove', ids);
+
 	// @todo Maybe return a more meaningful value.
 	/* jshint newcap: false */
 	return Q(true);
diff --git a/src/main.js b/src/main.js
index 3a5265d92..ae5fa339c 100644
--- a/src/main.js
+++ b/src/main.js
@@ -66,7 +66,7 @@ function json_api_call(session, message)
 		function (error) {
 			if (error instanceof Error)
 			{
-				console.error(error);
+				console.error(error.stack);
 				return format_error(Api.err.SERVER_ERROR);
 			}
 
diff --git a/src/model.js b/src/model.js
index 6a2f45c22..bfba52038 100644
--- a/src/model.js
+++ b/src/model.js
@@ -46,7 +46,7 @@ Model.prototype.get = function (property, def) {
  * Checks if a property exists.
  */
 Model.prototype.has = function (property) {
-	return (undefined !== this.get(property));
+	return (undefined !== this.properties[property]);
 };
 
 /**
@@ -64,7 +64,6 @@ Model.prototype.set = function (properties, value) {
 
 	var model = this;
 	_.each(properties, function (value, key) {
-
 		var prev = model.get(key);
 
 		// New value.
diff --git a/src/session.js b/src/session.js
index 7d57b90ea..5c7f002ff 100644
--- a/src/session.js
+++ b/src/session.js
@@ -14,8 +14,8 @@ var Session = Model.extend({
 
 		// If the user associated to this session is deleted or
 		// disabled, the session must close.
-		this.on('change:user_id', function (user_id) {
-			var event = 'user.revoked'+ user_id;
+		this.on('change:user_id', function () {
+			var event = 'user.revoked:'+ this.get('user_id');
 
 			xo.on(event, close);
 
@@ -27,8 +27,8 @@ var Session = Model.extend({
 
 		// If the token associated to this session is deleted, the
 		// session must close.
-		this.on('change:token_id', function (token_id) {
-			var event = 'token.revoked'+ token_id;
+		this.on('change:token_id', function () {
+			var event = 'token.revoked:'+ this.get('token_id');
 
 			xo.on(event, close);
 
diff --git a/src/xo.js b/src/xo.js
index 09520d25b..6fc6a7db0 100644
--- a/src/xo.js
+++ b/src/xo.js
@@ -1,6 +1,8 @@
+var _ = require('underscore');
 var crypto = require('crypto');
 var hashy = require('hashy');
 var Q = require('q');
+
 var Collection = require('./collection');
 var Model = require('./model');
 
@@ -149,14 +151,15 @@ function Xo()
 
 	// This events are used to automatically close connections if the
 	// associated credentials are invalidated.
+	var self = this;
 	this.tokens.on('remove', function (token_ids) {
-		token_ids.each(function (token_id) {
-			this.emit('token.revoked:'+ token_id);
+		_.each(token_ids, function (token_id) {
+			self.emit('token.revoked:'+ token_id);
 		});
 	});
 	this.users.on('remove', function (user_ids) {
-		user_ids.each(function (user_id) {
-			this.emit('user.revoked:'+ user_id);
+		_.each(user_ids, function (user_id) {
+			self.emit('user.revoked:'+ user_id);
 		});
 	});
 }