diff --git a/doc/requirements.txt b/doc/requirements.txt
index a02f880..2e44bfb 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,8 +1,4 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-
 openstackdocstheme>=2.2.0 # Apache-2.0
-sphinx>=2.0.0,!=2.1.0 # BSD
+sphinx>=2.0.0 # BSD
 reno>=3.1.0 # Apache-2.0
 sphinxcontrib-apidoc>=0.2.0  # BSD