diff --git a/appveyor.yml b/appveyor.yml
index e7c0786b..5eee221a 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -18,7 +18,7 @@ install:
   - pypy --version
 
   # Upgrade virtualenv for e.g. more-itertools to be handled properly.
-  - C:\Python35\python -m pip install -U virtualenv==16.6.1
+  - C:\Python35\python -m pip install -U virtualenv==16.6.0
   - C:\Python35\python -m pip install tox
 
 test_script: