diff --git a/tox.ini b/tox.ini
index e033f6e49..b8ac733f6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -35,9 +35,10 @@ deps =
 skip_install = True
 basepython = python3.8
 commands =
+    black --version
     black . --check
 deps =
-    black
+    black==20.8
 
 [testenv:typechecker]
 skip_install = True