diff --git a/tox.ini b/tox.ini
index 609be886..e68acd36 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,6 +14,7 @@ deps =
     nose
     nose-cov
     coveralls
+    pygments==2.1.3
 
 commands =
     {envpython} --version