diff --git a/path_test.go b/path_test.go
index 0c498182..b9c4e670 100644
--- a/path_test.go
+++ b/path_test.go
@@ -51,6 +51,7 @@ func TestPathBuilder(t *testing.T) {
 }
 
 func TestPathBuilderNoChain(t *testing.T) {
+	// See PR #420.
 	builder := yaml.PathBuilder{}
 	builder.Root()
 	builder.Child("a")