diff --git a/NEWS b/NEWS
index fedd601..84042a7 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,6 @@
 1.3.4.dev0
  * Part of #125: Color borgmatic (but not Borg) output when using an interactive terminal.
+ # #166: Run tests for all installed versions of Python.
  * #168: Update README with continuous integration badge.
  * #169: Automatically sort Python imports in code.
  * Document installing borgmatic with pip install --user instead of a system Python install.
diff --git a/scripts/black b/scripts/black
deleted file mode 100755
index 9320501..0000000
--- a/scripts/black
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/usr/bin/env sh
-
-if which black; then
-    black --skip-string-normalization --line-length 100 --check .
-else
-    echo "Skipping black due to not being installed."
-fi
diff --git a/scripts/isort b/scripts/isort
deleted file mode 100755
index c3b4378..0000000
--- a/scripts/isort
+++ /dev/null
@@ -1,3 +0,0 @@
-#!/usr/bin/env sh
-
-isort --recursive --check-only --settings-path setup.cfg .
diff --git a/tox.ini b/tox.ini
index 82b4c36..dbfc074 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,6 @@
 [tox]
-envlist = py3
+envlist = py35,py36,py37
+skip_missing_interpreters = True
 skipsdist = True
 minversion = 3.10.0
 
@@ -11,8 +12,8 @@ install_command =
     sh scripts/pip {opts} {packages}
 commands =
     pytest
-    sh scripts/black
-    sh scripts/isort
+    py36,py37: black --check .
+    isort --recursive --check-only --settings-path setup.cfg .
     flake8 .
 
 [testenv:black]