diff --git a/HACKING.adoc b/HACKING.adoc
index f9f4fdf63..d6a848d65 100644
--- a/HACKING.adoc
+++ b/HACKING.adoc
@@ -236,6 +236,20 @@ link:.travis.yml[]:
 CI_KIND=build XARCH=i386 bash -ex .travis-ci.sh
 ----
 
+The scripts support two other kinds of tests (values of the
+`CI_KIND` variable) which both inspect the patch submitted as part of
+a pull request. `tests` checks that the testsuite has been modified
+(hopefully, improved) by the patch, and `changes` checks that the
+link:Changes[] file has been modified (hopefully to add a new entry).
+
+These tests rely on the `$TRAVIS_COMMIT_RANGE` variable which you can
+set explicitly to reproduce them locally.
+
+The `changes` check can be disabled by including "(no change
+entry needed)" in one of your commit messages -- but in general all
+patches submitted should come with a Changes entry; see the guidelines
+in link:CONTRIBUTING.md[].
+
 ==== INRIA's Continuous Integration (CI)
 
 INRIA provides a Jenkins continuous integration service that OCaml