function pum_get_default_theme_id() {
	$default_theme_id = pum_get_option( 'default_theme_id' );

	if ( false === $default_theme_id ) {
		$default_theme_id = get_option( 'popmake_default_theme' );

		if ( false === $default_theme_id ) {
			$default_theme_id = pum_install_default_theme();
			if ( pum_update_option( 'default_theme_id', $default_theme_id ) ) {
				// Self cleanup old version.
				delete_option( 'popmake_default_theme' );
			}
		}
	}

	return absint( $default_theme_id );
}