diff --git a/Contributing.md b/Contributing.md
index 02919c2f..100b43ff 100644
--- a/Contributing.md
+++ b/Contributing.md
@@ -217,10 +217,16 @@ re-introduce a bug down the line.
 We use the [`pytest`](https://docs.pytest.org/en/stable/) for unit testing.
 
 The files for a test should go in a sub-directory of `tests/` named after the
-(principal) file or directory that contains the code they are testing.  e.g. for
-journal_lock.py the tests are in `tests/journal_lock.py/test_journal_lock.py`.
-The `test_` prefix on `test_journal_lock.py` is necessary in order for `pytest`
-to recognise the file as containing tests to be run.
+(principal) file or directory that contains the code they are testing.
+For example:
+
+- Tests for `journal_lock.py` are in
+   `tests/journal_lock.py/test_journal_lock.py`. The `test_` prefix on
+   `test_journal_lock.py` is necessary in order for `pytest` to recognise the
+   file as containing tests to be run.
+- Tests for `config/` code are located in `tests/config/test_config.py`, not
+   `tests/config.py/test_config.py`
+
 The sub-directory avoids having a mess of files in `tests`, particularly when
 there might be supporting files, e.g. `tests/config/_old_config.py` or files
 containing test data.