Use ‘full’ size for thumbnails in product page

Hello everyone,

I’m building a slideshow with all the images attached to a product. Before WC 3.3 everything worked fine.

Now the main image is still right, but additional images are loading in their thumbnail sizes.

I found this function wc_get_gallery_image_html() which seems to define the sizes of images.

For what I understand the following row does the job:

image_size = apply_filters( 'woocommerce_gallery_image_size', $flexslider || $main_image ? 'woocommerce_single': $thumbnail_size );

It says if is the main image 'woocommerce_single' (I think means ‘full’ size), else $thumbnail_size.

How can I control this part of the code, to get that ALL the images are loaded in their ‘full’ resolution in the product page?

Hope I’ve explained well. I’m still studying to became a developer. Thank you and sorry for any mistake in the message.