3 files changed, 18 insertions, 0 deletions
diff --git a/libdbusmenu-glib/client.c b/libdbusmenu-glib/client.c
index 44312a8..b0b1157 100644
--- a/libdbusmenu-glib/client.c
+++ b/libdbusmenu-glib/client.c
@@ -486,6 +486,8 @@ dbusmenu_client_new (const gchar * name, const gchar * object)
 DbusmenuMenuitem *
 dbusmenu_client_get_root (DbusmenuClient * client)
 {
+	g_return_val_if_fail(DBUSMENU_IS_CLIENT(client), NULL);
+
 	DbusmenuClientPrivate * priv = DBUSMENU_CLIENT_GET_PRIVATE(client);
 
 	if (priv->layoutcall != NULL) {
diff --git a/libdbusmenu-glib/menuitem.c b/libdbusmenu-glib/menuitem.c
index f228059..742fc93 100644
--- a/libdbusmenu-glib/menuitem.c
+++ b/libdbusmenu-glib/menuitem.c
@@ -198,6 +198,8 @@ dbusmenu_menuitem_new_with_id (guint id)
 guint
 dbusmenu_menuitem_get_id (DbusmenuMenuitem * mi)
 {
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(mi), 0);
+
 	GValue retval = {0};
 	g_value_init(&retval, G_TYPE_UINT);
 	g_object_get_property(G_OBJECT(mi), "id", &retval);
@@ -289,6 +291,9 @@ dbusmenu_menuitem_get_position (DbusmenuMenuitem * mi, DbusmenuMenuitem * parent
 gboolean
 dbusmenu_menuitem_child_append (DbusmenuMenuitem * mi, DbusmenuMenuitem * child)
 {
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(mi), FALSE);
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(child), FALSE);
+
 	DbusmenuMenuitemPrivate * priv = DBUSMENU_MENUITEM_GET_PRIVATE(mi);
 	priv->children = g_list_append(priv->children, child);
 	return TRUE;
@@ -308,6 +313,9 @@ dbusmenu_menuitem_child_append (DbusmenuMenuitem * mi, DbusmenuMenuitem * child)
 gboolean
 dbusmenu_menuitem_child_delete (DbusmenuMenuitem * mi, DbusmenuMenuitem * child)
 {
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(mi), FALSE);
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(child), FALSE);
+
 	DbusmenuMenuitemPrivate * priv = DBUSMENU_MENUITEM_GET_PRIVATE(mi);
 	priv->children = g_list_remove(priv->children, child);
 	return TRUE;
@@ -328,6 +336,9 @@ dbusmenu_menuitem_child_delete (DbusmenuMenuitem * mi, DbusmenuMenuitem * child)
 gboolean
 dbusmenu_menuitem_child_add_position (DbusmenuMenuitem * mi, DbusmenuMenuitem * child, guint position)
 {
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(mi), FALSE);
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(child), FALSE);
+
 	DbusmenuMenuitemPrivate * priv = DBUSMENU_MENUITEM_GET_PRIVATE(mi);
 	priv->children = g_list_insert(priv->children, child, position);
 	return TRUE;
@@ -347,6 +358,8 @@ dbusmenu_menuitem_child_add_position (DbusmenuMenuitem * mi, DbusmenuMenuitem *
 DbusmenuMenuitem *
 dbusmenu_menuitem_child_find (DbusmenuMenuitem * mi, guint id)
 {
+	g_return_val_if_fail(DBUSMENU_IS_MENUITEM(mi), NULL);
+
 	GList * childs = dbusmenu_menuitem_get_children(mi);
 	if (childs == NULL) return NULL;
 
diff --git a/libdbusmenu-glib/server.c b/libdbusmenu-glib/server.c
index bb5bd8d..3db6db0 100644
--- a/libdbusmenu-glib/server.c
+++ b/libdbusmenu-glib/server.c
@@ -317,6 +317,9 @@ dbusmenu_server_new (const gchar * object)
 void
 dbusmenu_server_set_root (DbusmenuServer * self, DbusmenuMenuitem * root)
 {
+	g_return_if_fail(DBUSMENU_IS_SERVER(self));
+	g_return_if_fail(DBUSMENU_IS_MENUITEM(root));
+
 	g_debug("Setting root object: 0x%X", (unsigned int)root);
 	GValue rootvalue = {0};
 	g_value_init(&rootvalue, G_TYPE_OBJECT);