diff --git a/gtk/gtkpopover.c b/gtk/gtkpopover.c
index d0c73bb759..003aebb737 100644
--- a/gtk/gtkpopover.c
+++ b/gtk/gtkpopover.c
@@ -379,6 +379,40 @@ allocate_contents (GtkGizmo *gizmo,
                               }, -1);
 }
 
+static void
+activate_default_cb (GSimpleAction *action,
+                     GVariant      *parameter,
+                     gpointer       data)
+{
+  GtkPopover *popover = data;
+  GtkPopoverPrivate *priv = gtk_popover_get_instance_private (popover);
+  GtkWidget *focus_widget;
+
+  focus_widget = gtk_root_get_focus (gtk_widget_get_root (priv->relative_to));
+  if (priv->default_widget && gtk_widget_is_sensitive (priv->default_widget) &&
+      (!focus_widget || !gtk_widget_get_receives_default (focus_widget)))
+    gtk_widget_activate (priv->default_widget);
+  else if (focus_widget && gtk_widget_is_sensitive (focus_widget))
+    gtk_widget_activate (focus_widget);
+}
+
+static void
+add_actions (GtkPopover *popover)
+{
+  GActionEntry entries[] = {
+    { "activate-default", activate_default_cb, NULL, NULL, NULL },
+  };
+
+  GActionGroup *actions;
+
+  actions = G_ACTION_GROUP (g_simple_action_group_new ());
+  g_action_map_add_action_entries (G_ACTION_MAP (actions),
+                                   entries, G_N_ELEMENTS (entries),
+                                   popover);
+  gtk_widget_insert_action_group (GTK_WIDGET (popover), "gtk", actions);
+  g_object_unref (actions);
+}
+
 static void
 gtk_popover_init (GtkPopover *popover)
 {
@@ -407,6 +441,8 @@ gtk_popover_init (GtkPopover *popover)
 
   context = gtk_widget_get_style_context (GTK_WIDGET (popover));
   gtk_style_context_add_class (context, GTK_STYLE_CLASS_BACKGROUND);
+
+  add_actions (popover);
 }
 
 static void
@@ -1259,5 +1295,7 @@ void
 gtk_popover_set_default_widget (GtkPopover *popover,
                                 GtkWidget  *widget)
 {
-  // FIXME
+  GtkPopoverPrivate *priv = gtk_popover_get_instance_private (popover);
+
+  priv->default_widget = widget;
 }