diff --git a/requirements.txt b/requirements.txt
index 9c4a708a07..3f15762885 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,5 @@
-pbr>=0.5.21,<1.0
+# 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>=1.8 # Apache-2.0
 Jinja2>=2.8 # BSD License (3 clause)
diff --git a/setup.py b/setup.py
index 70c2b3f32b..782bb21f06 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # Copyright (c) 2013 Hewlett-Packard Development Company, L.P.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -17,6 +16,14 @@
 # THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
+# In python < 2.7.4, a lazy loading of package `pbr` will break
+# setuptools if some other modules registered functions in `atexit`.
+# solution from: http://bugs.python.org/issue15881#msg170215
+try:
+    import multiprocessing  # noqa
+except ImportError:
+    pass
+
 setuptools.setup(
-    setup_requires=['pbr'],
+    setup_requires=['pbr>=1.8'],
     pbr=True)
diff --git a/test-requirements.txt b/test-requirements.txt
index c3726e8bfe..6489b16c7e 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1 +1,4 @@
-pyyaml
+# 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.
+PyYAML>=3.10.0 # MIT