diff --git a/src/Application.vala b/src/Application.vala
index 6c10029..63f4858 100644
--- a/src/Application.vala
+++ b/src/Application.vala
@@ -168,7 +168,26 @@ public class Application : Gtk.Application {
     }
 
     public void on_open_document () {
-        var open_dialog = new Gtk.FileDialog ();
+        var all_files_filter = new Gtk.FileFilter () {
+            name = _("All files"),
+        };
+        all_files_filter.add_pattern ("*");
+
+        var text_files_filter = new Gtk.FileFilter () {
+            name = _("Text files"),
+        };
+        text_files_filter.add_mime_type ("text/plain");
+
+        var filter_model = new ListStore (typeof (Gtk.FileFilter));
+        filter_model.append (all_files_filter);
+        filter_model.append (text_files_filter);
+
+        var open_dialog = new Gtk.FileDialog () {
+            default_filter = text_files_filter,
+            filters = filter_model,
+            title = _("Open"),
+        };
+
         open_dialog.open.begin (this.active_window, null, (obj, res) => {
             try {
                 var file = open_dialog.open.end (res);
diff --git a/src/Window.vala b/src/Window.vala
index 1e63147..60e1481 100644
--- a/src/Window.vala
+++ b/src/Window.vala
@@ -145,7 +145,24 @@ public class AppWindow : Gtk.Window {
         File oldfile = this.file;
         bool is_unsaved_doc = (Application.data_dir_path in this.file.get_path ());
 
+        var all_files_filter = new Gtk.FileFilter () {
+            name = _("All files"),
+        };
+        all_files_filter.add_pattern ("*");
+
+        var text_files_filter = new Gtk.FileFilter () {
+            name = _("Text files"),
+        };
+        text_files_filter.add_mime_type ("text/plain");
+
+        var filter_model = new ListStore (typeof (Gtk.FileFilter));
+        filter_model.append (all_files_filter);
+        filter_model.append (text_files_filter);
+
         var save_dialog = new Gtk.FileDialog () {
+            default_filter = text_files_filter,
+            filters = filter_model,
+            title = _("Save as"),
             initial_name = (is_unsaved_doc ? file_name + ".txt" : file_name)
         };