diff --git a/appveyor.yml b/appveyor.yml
index 3c403d1e9..ca292ec43 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -20,6 +20,10 @@ environment:
       TOXENV: "py36-cov"
       TOXPYTHON: "C:\\Python36-x64\\python.exe"
 
+# Do not build feature branches with open Pull Requests after the initial 
+# opening of a PR.
+skip_branch_with_pr: true
+
 install:
   # If there is a newer build queued for the same PR, cancel this one.
   # The AppVeyor 'rollout builds' option is supposed to serve the same