diff --git a/requirements.txt b/requirements.txt
index cb199b59..ffc47449 100644
--- a/requirements.txt
+++ b/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.
 pbr>=0.6,!=0.7,<1.0
 argparse
 iso8601>=0.1.9
diff --git a/test-requirements.txt b/test-requirements.txt
index 41a81863..1bdbb36c 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.
 # Hacking already pins down pep8, pyflakes and flake8
 hacking>=0.9.1,<0.10
 coverage>=3.6