diff --git a/nav2_costmap_2d/src/costmap_layer.cpp b/nav2_costmap_2d/src/costmap_layer.cpp
index 3f9da4013d8..ad488c26185 100644
--- a/nav2_costmap_2d/src/costmap_layer.cpp
+++ b/nav2_costmap_2d/src/costmap_layer.cpp
@@ -55,6 +55,7 @@ void CostmapLayer::touch(
 
 void CostmapLayer::matchSize()
 {
+  std::lock_guard<Costmap2D::mutex_t> guard(*getMutex());
   Costmap2D * master = layered_costmap_->getCostmap();
   resizeMap(
     master->getSizeInCellsX(), master->getSizeInCellsY(), master->getResolution(),