diff --git a/tox.ini b/tox.ini
index 434677371..f5b683f48 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,6 +39,8 @@ commands =
 basepython = python2.7
 commands =
   bash tools/flake8wrap.sh {posargs}
+  # Check that all JSON files don't have \r\n in line.
+  bash -c "! find doc/ -type f -name *.json | xargs grep -U -n $'\r'"
   # 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'