diff --git a/src/libslic3r/SLA/Hollowing.cpp b/src/libslic3r/SLA/Hollowing.cpp
index 1d3016bde8..32a8810375 100644
--- a/src/libslic3r/SLA/Hollowing.cpp
+++ b/src/libslic3r/SLA/Hollowing.cpp
@@ -1,4 +1,5 @@
 #include <functional>
+#include <optional>
 
 #include <libslic3r/OpenVDBUtils.hpp>
 #include <libslic3r/TriangleMesh.hpp>
diff --git a/src/libslic3r/SLA/SupportTreeBuildsteps.hpp b/src/libslic3r/SLA/SupportTreeBuildsteps.hpp
index 013666f074..478e2df1fe 100644
--- a/src/libslic3r/SLA/SupportTreeBuildsteps.hpp
+++ b/src/libslic3r/SLA/SupportTreeBuildsteps.hpp
@@ -2,6 +2,7 @@
 #define SLASUPPORTTREEALGORITHM_H
 
 #include <cstdint>
+#include <optional>
 
 #include <libslic3r/SLA/SupportTreeBuilder.hpp>
 #include <libslic3r/SLA/Clustering.hpp>