diff --git a/tox.ini b/tox.ini
index 391c47d0..90fdae27 100644
--- a/tox.ini
+++ b/tox.ini
@@ -40,7 +40,9 @@ commands =
 
 [testenv:py36-docs]
 changedir = doc
-extras = docs
+extras =
+    docs
+    plotly
 commands =
     # remove autosummary output
     rm -rf {toxinidir}/doc/source/_neurom_build