diff --git a/tox.ini b/tox.ini
index 0a989c21..8f1b1df3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -30,6 +30,7 @@ python =
 deps =
     black
     flake8
+    isort
     pytest
     pytest-timeout
 commands = {envpython} run_tests {posargs}