diff --git a/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp b/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp
index 04d4b99ab..1b25c4ac9 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoSimplify.hpp
@@ -7,6 +7,7 @@
 #include "admesh/stl.h" // indexed_triangle_set
 #include <thread>
 #include <optional>
+#include <atomic>
 
 namespace Slic3r {