diff --git a/requirements.txt b/requirements.txt
index 770417f..4b4ea12 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,5 @@
+# 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.
 argparse
 pbr>=0.6,!=0.7,<1.0
diff --git a/test-requirements.txt b/test-requirements.txt
index c9f3ff5..4282c69 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>=0.9.2,<0.10
 
 Babel>=1.3