diff --git a/src/libslic3r/QuadricEdgeCollapse.cpp b/src/libslic3r/QuadricEdgeCollapse.cpp
index a66dbc192..95c7b40d8 100644
--- a/src/libslic3r/QuadricEdgeCollapse.cpp
+++ b/src/libslic3r/QuadricEdgeCollapse.cpp
@@ -1,5 +1,6 @@
 #include "QuadricEdgeCollapse.hpp"
 #include <tuple>
+#include <optional>
 #include "MutablePriorityQueue.hpp"
 #include "SimplifyMeshImpl.hpp"
 #include <tbb/parallel_for.h>