diff --git a/.gitignore b/.gitignore
index 403d6606df..6405e04ecf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,3 +29,6 @@ __pycache__
 
 # Test results from 'make test'
 test-output.json
+
+# Binary downloaded when acceptance tests are run.
+tools/yamlfmt