diff --git a/test-requirements.txt b/test-requirements.txt
index 218c718..379ca9f 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -6,5 +6,5 @@ bashate>=0.2 # Apache-2.0
 hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 
 docutils>=0.11 # OSI-Approved Open Source, Public Domain
-sphinx>=1.5.1 # BSD
+sphinx!=1.6.1,>=1.5.1 # BSD
 oslosphinx>=4.7.0 # Apache-2.0