diff --git a/test-requirements.txt b/test-requirements.txt
index f7106b4..12333e6 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -6,7 +6,7 @@ coverage>=4.0 # Apache-2.0
 discover
 fixtures>=3.0.0 # Apache-2.0/BSD
 python-subunit>=0.0.18 # Apache-2.0/BSD
-sphinx>=1.5.1 # BSD
+sphinx==1.5.6 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 oslo.config>=3.22.0 # Apache-2.0