diff --git a/setup.cfg b/setup.cfg
index 180eabff..571f538b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -41,6 +41,7 @@ install_requires =
 
 [options.extras_require]
 dev =
+    black==19.10b0 ; python_version >= '3.6'
     flake8==3.7.9
     Flask-Testing==0.8.0
     pytest==5.4.1
diff --git a/tox.ini b/tox.ini
index 0db58d31..b5ff7055 100644
--- a/tox.ini
+++ b/tox.ini
@@ -22,7 +22,6 @@ changedir = {toxinidir}
 
 [testenv:black]
 commands = black --check --target-version=py34 .
-deps = black
 changedir = {toxinidir}
 
 [testenv:flake8]