diff --git a/test-requirements.txt b/test-requirements.txt
index 969944637..9a1ab966c 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,7 +1,7 @@
 # needed for doc build
 docutils>=0.11,!=0.13.1  # OSI-Approved Open Source, Public Domain
 openstackdocstheme>=1.25.0  # Apache 2.0
-sphinx>=1.5.0
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2
 PyYAML>=3.1.0
 yamllint>=0.5.2
 requests-cache