#define GTK_TREE_MODEL_SORT(obj) (GTK_CHECK_CAST ((obj), GTK_TYPE_TREE_MODEL_SORT, GtkTreeModelSort))
#define GTK_TREE_MODEL_SORT_CLASS(klass) (GTK_CHECK_CLASS_CAST ((klass), GTK_TYPE_TREE_MODEL_SORT, GtkTreeModelSortClass))
#define GTK_IS_TREE_MODEL_SORT(obj) (GTK_CHECK_TYPE ((obj), GTK_TYPE_TREE_MODEL_SORT))
-#define GTK_IS_TREE_MODEL_SORT_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((obj), GTK_TYPE_TREE_MODEL_SORT))
+#define GTK_IS_TREE_MODEL_SORT_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), GTK_TYPE_TREE_MODEL_SORT))
#define GTK_TREE_MODEL_SORT_GET_CLASS(obj) (GTK_CHECK_GET_CLASS ((obj), GTK_TYPE_TREE_MODEL_SORT, GtkTreeModelSortClass))
typedef struct _GtkTreeModelSort GtkTreeModelSort;