diff --git a/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp b/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp
index e6367ee27..a2f819387 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp
@@ -7,6 +7,7 @@
 #include "slic3r/GUI/3DScene.hpp"
 #include "admesh/stl.h" // indexed_triangle_set
 #include <mutex>
+#include <thread>
 
 namespace Slic3r {
 class ModelVolume;