diff --git a/tox.ini b/tox.ini
index 84f619d..e89201a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,7 +18,7 @@ commands =
 [testenv:black]
 skip_install = true
 deps =
-  black
+  black==19.10b0
 commands =
   {envpython} -m black --check swh