diff --git a/requirements-py3.txt b/requirements-py3.txt
index af65f46..426cb94 100644
--- a/requirements-py3.txt
+++ b/requirements-py3.txt
@@ -1,3 +1,7 @@
+# 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
 Babel>=0.9.6
 iso8601>=0.1.9
diff --git a/requirements.txt b/requirements.txt
index a3dfbfb..e5a8987 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,7 @@
+# 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.
+
 Babel>=0.9.6
 iso8601>=0.1.9
 eventlet>=0.13.0
diff --git a/test-requirements.txt b/test-requirements.txt
index 95ce56d..ef8f44c 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,3 +1,7 @@
+# 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>=0.9.1,<0.10
 oslotest