8 – Access custom fields in rules_entity_insert: comment event

In Rules 8, I know how to make user-defined fields of a content type available in a post-update event (rules_entity_update: node) event:

Condition: The unit consists of a bundle
Entity: node
Type: node
Bundle: my_content_type

So I can use something like {{node.my_custom_field.value}}.

When I'm in an event "After saving a new comment (rules_entity_insert: comment)", the above solution does not work. How should I do this (access custom fields of the node to which the comment is attached)?