diff --git a/tox.ini b/tox.ini
index 6d0016c0..e29d5856 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,6 +27,10 @@ deps =
     -rtest_requirements.txt
     -roptional_requirements.txt
 
+[testenv:{py36,py37,py38,py39}-doctest]
+commands =
+    py36,py37,py38,py39: nosetests -v --with-doctest --doctest-options=+NORMALIZE_WHITESPACE petl -I"csv_py2\.py" -I"db\.py"
+
 [testenv:{py37,py38,py39}-docs]
 # build documentation under similar environment to readthedocs
 changedir = docs