diff --git a/tox.ini b/tox.ini
index 2cffe80..bcdc65f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -33,11 +33,11 @@ commands = flake8 {posargs} flake8/
 [testenv:release]
 basepython = python2.7
 deps =
-    twine >= 1.4.0
+    twine >= 1.5.0
     wheel
 commands =
     python setup.py sdist bdist_wheel
-    twine upload {posargs} dist/*
+    twine upload --skip-existing {posargs} dist/*
 
 [flake8]
 select = E,F,W