diff --git a/docs/userguide/package_discovery.rst b/docs/userguide/package_discovery.rst
index c33877e1f6..2e39a41d2d 100644
--- a/docs/userguide/package_discovery.rst
+++ b/docs/userguide/package_discovery.rst
@@ -50,7 +50,9 @@ Normally, you would specify the packages to be included manually in the followin
 
 
 If your packages are not in the root of the repository or do not correspond
-exactly to the directory structure, you also need to configure ``package_dir``:
+exactly to the directory structure (that is, the directory layout in your
+repository does not match the dotted package hierarchy you want installed on
+the end-user's machine), you also need to configure ``package_dir``:
 
 .. tab:: setup.cfg
 
diff --git a/newsfragments/4109.doc.rst b/newsfragments/4109.doc.rst
new file mode 100644
index 0000000000..3c2ee49187
--- /dev/null
+++ b/newsfragments/4109.doc.rst
@@ -0,0 +1,2 @@
+Clarified what "correspond exactly to the directory structure" means in
+the ``packages`` section of the Package Discovery user guide.