diff --git a/test-requirements.txt b/test-requirements.txt
index ed43223..fbdfb19 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -4,7 +4,7 @@
 
 hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 
 # releasenotes