diff --git a/network/health/tracker.go b/network/health/tracker.go
index 69fdb0b13e01cdb032138ba2ef51f8d90448bb09..1cc4be54ef3e0ddb444a50a6a00570885ddcf659 100644
--- a/network/health/tracker.go
+++ b/network/health/tracker.go
@@ -144,6 +144,7 @@ func (t *Tracker) setHealth(h bool) {
 func (t *Tracker) Start() (stoppable.Stoppable, error) {
 	t.mux.Lock()
 	if t.running {
+		t.mux.Unlock()
 		return nil, errors.New("cannot start Health tracker threads, " +
 			"they are already running")
 	}