diff --git a/ci/templates/appveyor.yml b/ci/templates/appveyor.yml
index 6bfce9ae..f5cd7ab2 100644
--- a/ci/templates/appveyor.yml
+++ b/ci/templates/appveyor.yml
@@ -23,8 +23,8 @@ install:
   - pypy --version
 
   # Upgrade virtualenv for e.g. more-itertools to be handled properly.
-  # Pin it to work around https://github.com/tox-dev/tox/issues/1389.
-  - C:\Python35\python -m pip install -U virtualenv==16.5.0
+  # Pin it to avoid side-effects.
+  - C:\Python35\python -m pip install -U virtualenv==16.7.0
   - C:\Python35\python -m pip install tox
 
 test_script: