diff --git a/Doc/library/packaging.util.rst b/Doc/library/packaging.util.rst
index 019f3e9..ae96d87 100644
--- a/Doc/library/packaging.util.rst
+++ b/Doc/library/packaging.util.rst
@@ -121,9 +121,12 @@
 .. function:: byte_compile(py_files[, optimize=0, force=0, prefix=None, base_dir=None, verbose=1, dry_run=0, direct=None])
 
    Byte-compile a collection of Python source files to either :file:`.pyc` or
-   :file:`.pyo` files in the same directory.  *py_files* is a list of files to
-   compile; any files that don't end in :file:`.py` are silently skipped.
-   *optimize* must be one of the following:
+   :file:`.pyo` files in a :file:`__pycache__` subdirectory (see :pep:`3147`),
+   or to the same directory when using the distutils2 backport on Python
+   versions older than 3.2.
+
+   *py_files* is a list of files to compile; any files that don't end in
+   :file:`.py` are silently skipped.  *optimize* must be one of the following:
 
    * ``0`` - don't optimize (generate :file:`.pyc`)
    * ``1`` - normal optimization (like ``python -O``)