diff --git a/tox.ini b/tox.ini
index 4a353e12ce..f5c1b5ea06 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,6 +27,8 @@ basepython = python2.7
 deps = hacking
 commands =
   bash tools/flake8wrap.sh {posargs}
+  # Check that all included JSON files are valid JSON
+  bash -c '! find doc/ -type f -name *.json | xargs -t -n1 python -m json.tool 2>&1 > /dev/null | grep -B1 -v ^python'
 
 [testenv:py34]
 # NOTE(mriedem): If py34 fails with "db type could not be determined", delete
@@ -94,6 +96,7 @@ commands = {posargs}
 commands =
   rm -rf doc/source/api doc/build api-guide/build api-ref/build
   python setup.py build_sphinx
+  # Check that all included JSON files are valid JSON
   bash -c '! find doc/ -type f -name *.json | xargs -t -n1 python -m json.tool 2>&1 > /dev/null | grep -B1 -v ^python'
   oslo-config-generator --config-file=etc/nova/nova-config-generator.conf
   oslopolicy-sample-generator --config-file=etc/nova/nova-policy-generator.conf