Fix custon font settings

Hello!
I added custon font by following code:

add_filter( 'avf_google_heading_font',  'avia_add_heading_font');
function avia_add_heading_font($fonts)
{
        $fonts['PT Sans'] = 'PT Sans:400,700,400italic,700italic&subset=cyrillic';
	return $fonts;
}

add_filter( 'avf_google_content_font',  'avia_add_content_font');
function avia_add_content_font($fonts)
{
        $fonts['PT Sans'] = 'PT Sans:400,700,400italic,700italic&subset=cyrillic';
	return $fonts;
}

But every time I reload Enfold settings page, it sets the font setting to default – so my font disables: http://prntscr.com/2hihtm
Is there any way to make my font settings permanent?
Thank you!