diff --git a/doc/snac.8 b/doc/snac.8
index e8a3562..8e207ce 100644
--- a/doc/snac.8
+++ b/doc/snac.8
@@ -255,7 +255,9 @@ all posts' content will be matched against these regexes, one by one, and
 any match will make the post to be rejected. If you don't know about regular
 expressions, don't use this option (or learn about them in some tutorial,
 there are gazillions of them out there), as you and your users may start
-missing posts.
+missing posts. Also, given that every regular expression implementation
+supports a different set of features, consider reading the documentation
+about the one implemented in your system.
 .Ss ActivityPub Support
 These are the following activities and objects that
 .Nm