diff --git a/test-requirements.txt b/test-requirements.txt
index fd9f1f9f54..3b6c2021ec 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,3 +1,6 @@
+# The order of packages is significant, because pip processes them in the order
+# of appearance. Changing the order has an impact on the overall integration
+# process, which may cause wedges in the gate later.
 Jinja2
 doc8  # Apache-2.0
 openstack-doc-tools>=0.18.1