protected function register_default_types() {
		require_once "{$this->dir}/includes/fontpack.php";
		Icon_Picker_Fontpack::instance();

		/**
		 * Allow themes/plugins to disable one or more default types
		 *
		 * @since 0.1.0
		 * @param array $default_types Default icon types.
		 */
		$default_types = array_filter( (array) apply_filters( 'icon_picker_default_types', $this->default_types ) );

		/**
		 * Validate filtered default types
		 */
		$default_types = array_intersect( $this->default_types, $default_types );

		if ( empty( $default_types ) ) {
			return;
		}

		foreach ( $default_types as $filename => $class_suffix ) {
			$class_name = "Icon_Picker_Type_{$class_suffix}";

			require_once "{$this->dir}/includes/types/{$filename}.php";
			$this->registry->add( new $class_name() );
		}
	}