diff --git a/requirements.txt b/requirements.txt
index 082ee58418..cc8b9e1989 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.
+
 pbr>=0.6,!=0.7,<1.0
 SQLAlchemy>=0.8.4,<=0.8.99,>=0.9.7,<=0.9.99
 anyjson>=0.3.3
diff --git a/test-requirements.txt b/test-requirements.txt
index a6da658e73..e1b09ecb98 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>=0.9.2,<0.10
 coverage>=3.6
 discover