diff --git a/requirements.txt b/requirements.txt
index 4f71e96..22c195d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,9 +2,9 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-pbr>=2.0.0  # Apache-2.0
+pbr!=2.1.0,>2.0.0  # Apache-2.0
 
 oslosphinx>=4.7.0 # Apache-2.0
-sphinx>=1.5.1,<1.6 # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
 
 yasfb>=0.5.1