diff --git a/pkg/minikube/download/download.go b/pkg/minikube/download/download.go
index 26ede425ee..36e201fb71 100644
--- a/pkg/minikube/download/download.go
+++ b/pkg/minikube/download/download.go
@@ -101,6 +101,7 @@ func withinUnitTest() bool {
 	return flag.Lookup("test.v") != nil || strings.HasSuffix(os.Args[0], "test")
 }
 
+// lockDownload locks `file` if possible and returns a releaser that must be called to release the lock.
 func lockDownload(file string) (mutex.Releaser, error) {
 	type retPair struct {
 		mutex.Releaser