Incorrect width and height “Post Thumbnail”

Hello.

URL Image corrrect, but width and height incorrect. Found a solution https://wordpress.stackexchange.com/questions/167308/function-to-get-url-of-original-uploaded-image-full-size/167309

Original code:

if( has_post_thumbnail() ) {
            $thumbnail = wp_get_attachment_image_src( get_post_thumbnail_id( null ) );

Working for me:

if( has_post_thumbnail() ) {
            $thumbnail = wp_get_attachment_image_src( get_post_thumbnail_id( null ), 'full', false );

Sorry for My English