diff --git a/tox.ini b/tox.ini
index 262d04751..f4a78741c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -71,7 +71,7 @@ deps =
 whitelist_externals =
     {[testenv]whitelist_externals}
     isort
-commands = isort --recursive --check-only deluge docs win32 *.py
+commands = python -c "import subprocess, sys; output = subprocess.check_output('isort --recursive --diff --stdout  deluge docs win32 *.py', shell=True); print output; sys.exit(len(output) != 0)"
 
 [testenv:flake8]
 setenv = {[testenv]setenv}