diff --git a/requirements.txt b/requirements.txt
index 9ec997a88c..604b4bee60 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,9 +7,9 @@
 # be installed in a specific order.
 #
 # PBR should always appear first
-pbr>=2.0.0 # Apache-2.0
+pbr!=2.1.0,>=2.0.0 # Apache-2.0
 # Horizon Core Requirements
-Babel>=2.3.4 # BSD
+Babel!=2.4.0,>=2.3.4 # BSD
 Django<1.9,>=1.8 # BSD
 Pint>=0.5 # BSD
 django-babel>=0.5.1 # BSD