diff --git a/plugins/kolab_files/kolab_files.js b/plugins/kolab_files/kolab_files.js
index 59f767fe..46df8799 100644
--- a/plugins/kolab_files/kolab_files.js
+++ b/plugins/kolab_files/kolab_files.js
@@ -113,13 +113,17 @@ window.rcmail && window.files_api && rcmail.addEventListener('init', function()
 
       if (rcmail.env.action == 'edit' && rcmail.env.file_data.viewer && rcmail.env.file_data.viewer.manticore)
         manticore = new manticore_api({
+          // UI elements
           iframe: $('#fileframe').get(0),
           export_menu: rcmail.gui_objects.exportmenu ? $('ul', rcmail.gui_objects.exportmenu).get(0) : null,
           title_input: $('#document-title').get(0),
           members_list: $('#members').get(0),
           photo_url: '?_task=addressbook&_action=photo&_email=%email',
           photo_default_url: rcmail.env.photo_placeholder,
+          // events
           ready: function(data) { manticore_init(); },
+          documentChanged: function(data) { rcmail.enable_command('document-save', true); },
+          // notifications/alerts
           set_busy: function(state, message) { return rcmail.set_busy(state, message ? 'kolab_files.' + message : ''); },
           hide_message: function(id) { return rcmail.hide_message(id); },
           display_message: function(label, type) { return rcmail.display_message('kolab_files.' + label, type); },
@@ -1124,15 +1128,17 @@ function manticore_init()
 {
   var info = rcmail.env.file_data;
 
-  rcmail.enable_command('document-save', 'document-export', true);
+  rcmail.enable_command('document-export', true);
 
   if (info && info.session && info.session.is_owner)
-    rcmail.enable_command('files-close', 'document-editors', true);
+    rcmail.enable_command('document-close', 'document-editors', true);
 };
 
 rcube_webmail.prototype.document_save = function()
 {
-  manticore.save();
+  manticore.save(function(data) {
+    rcmail.enable_command('document-save', false);
+  });
 };
 
 rcube_webmail.prototype.document_export = function(type)
@@ -1151,10 +1157,13 @@ rcube_webmail.prototype.document_editors = function()
 };
 
 // close editing session
-rcube_webmail.prototype.files_close = function()
+rcube_webmail.prototype.document_close = function()
 {
-    // @todo: check document "unsaved changes" state and display a warning
-    file_api.document_delete(this.env.file_data.session.id);
+  // check document "unsaved changes" state and display a warning
+  if (this.commands['document-save'] && !confirm(this.gettext('kolab_files.unsavedchanges')))
+    return;
+
+  file_api.document_delete(this.env.file_data.session.id);
 };
 
 // document editors management dialog
diff --git a/plugins/kolab_files/lib/kolab_files_engine.php b/plugins/kolab_files/lib/kolab_files_engine.php
index efa70769..fda250ce 100644
--- a/plugins/kolab_files/lib/kolab_files_engine.php
+++ b/plugins/kolab_files/lib/kolab_files_engine.php
@@ -950,7 +950,7 @@ class kolab_files_engine
      */
     protected function action_edit()
     {
-        $this->plugin->add_label('sessionterminating');
+        $this->plugin->add_label('sessionterminating', 'unsavedchanges');
 
         $this->file_opener(intval($_GET['_viewer']));
     }
diff --git a/plugins/kolab_files/localization/en_US.inc b/plugins/kolab_files/localization/en_US.inc
index a2812d2b..88ba16c6 100644
--- a/plugins/kolab_files/localization/en_US.inc
+++ b/plugins/kolab_files/localization/en_US.inc
@@ -105,6 +105,7 @@ $labels['select'] = 'Select';
 $labels['terminatesession'] = 'Terminate the session';
 $labels['terminate'] = 'Terminate';
 $labels['sessionterminating'] = 'Terminating the session...';
+$labels['unsavedchanges'] = 'There are unsaved changes in the document that will be lost. Do you want to terminate the session anyway?';
 $labels['manageeditors'] = 'Invite to document';
 $labels['participant'] = 'Participant';
 $labels['status'] = 'Status';
diff --git a/plugins/kolab_files/skins/larry/templates/docedit.html b/plugins/kolab_files/skins/larry/templates/docedit.html
index cbcd3ef9..90629786 100644
--- a/plugins/kolab_files/skins/larry/templates/docedit.html
+++ b/plugins/kolab_files/skins/larry/templates/docedit.html
@@ -18,7 +18,7 @@
 <!--
     <roundcube:button command="files-delete" type="link" class="button delete disabled" classAct="button delete" classSel="button delete pressed" label="delete" title="kolab_files.deletefile" />
 -->
-    <roundcube:button command="files-close" type="link" class="button delete disabled" classAct="button delete" classSel="button delete pressed" label="kolab_files.terminate" title="kolab_files.terminatesession" />
+    <roundcube:button command="document-close" type="link" class="button delete disabled" classAct="button delete" classSel="button delete pressed" label="kolab_files.terminate" title="kolab_files.terminatesession" />
     <span class="dropbutton">
         <roundcube:button command="document-export" type="link" class="button export disabled" classAct="button export" classSel="button export pressed" label="kolab_files.get" title="kolab_files.getfile" />
         <a href="#export" class="dropbuttontip" id="exportmenulink" onclick="UI.toggle_popup('exportmenu',event);return false" aria-haspopup="true" aria-expanded="false" aria-owns="exportmenu-menu" tabindex="0">Export options</a>