diff --git a/source/guides/migrating-to-pypi-org.rst b/source/guides/migrating-to-pypi-org.rst
index 2b565e8ee..a9f91365c 100644
--- a/source/guides/migrating-to-pypi-org.rst
+++ b/source/guides/migrating-to-pypi-org.rst
@@ -135,6 +135,12 @@ Downloading packages
 
 ``pypi.org`` is the default host for downloading packages.
 
+If downloads still use the old ``pypi.python.org`` host, check whether a
+:file:`pip.conf` file or the ``PIP_INDEX_URL`` environment variable overrides
+pip's default index URL. See pip's
+:ref:`configuration documentation <pip:config-file>` for the locations and
+available settings.
+
 Managing published packages and releases
 ----------------------------------------