diff --git a/tox.ini b/tox.ini
index 44c84cd0f2e0..82a78bc4aa3b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -160,8 +160,10 @@ commands =
 [testenv:docs]
 description =
   Build main documentation.
+# Note that we don't use {[testenv]deps} for deps here because we don't want
+# to install (test-)requirements.txt for docs.
 deps =
-  {[testenv]deps}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf doc/build/html doc/build/doctrees