diff --git a/storage/remote/queue_manager_test.go b/storage/remote/queue_manager_test.go
index c76143c848..a707e806ad 100644
--- a/storage/remote/queue_manager_test.go
+++ b/storage/remote/queue_manager_test.go
@@ -1315,6 +1315,8 @@ func (c *TestWriteClient) GetProtoVersions(_ context.Context) (string, error) {
 }
 
 func (c *TestWriteClient) GetLastRWHeader() string {
+	c.mtx.Lock()
+	defer c.mtx.Unlock()
 	c.currstep++
 	if len(c.steps) > 0 {
 		return c.steps[c.currstep].lastRWHeader