diff --git a/cloud/shepherd/manager/initializer_test.go b/cloud/shepherd/manager/initializer_test.go
index 5ba2253..9545b5f 100644
--- a/cloud/shepherd/manager/initializer_test.go
+++ b/cloud/shepherd/manager/initializer_test.go
@@ -83,6 +83,8 @@
 		}
 	}
 
+	provider.muMachines.RLock()
+	defer provider.muMachines.RUnlock()
 	for _, m := range provider.machines {
 		if !m.agentStarted {
 			t.Fatalf("Initializer didn't start agent on machine %q", m.id)