diff --git a/requirements.txt b/requirements.txt
index 26a7a5c..7f2a83e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,6 @@
 # process, which may cause wedges in the gate later.
 
 # this is required for the docs build jobs
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0