diff --git a/doc/source/index.rst b/doc/source/index.rst
index 899c50b..4b4f1a4 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -15,6 +15,7 @@ reasons (for example in isolating cross-project performance issues).
    background
    api
    integration
+   collectors
    similar_projects
 
 Release Notes
diff --git a/setup.cfg b/setup.cfg
index 51c9f93..194729e 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -33,6 +33,7 @@ oslo_config =
 all_files = 1
 build-dir = doc/build
 source-dir = doc/source
+warning-is-error = 1
 
 [entry_points]
 oslo.config.opts =
diff --git a/test-requirements.txt b/test-requirements.txt
index 7170d29..89306a8 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -8,7 +8,7 @@ testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT
 
 oslosphinx>=4.7.0 # Apache-2.0
-sphinx>=1.2.1,!=1.3b1,<1.4 # BSD
+sphinx>=1.6.2 # BSD
 
 # Bandit security code scanner
 bandit>=1.1.0 # Apache-2.0