diff --git a/xs/src/libslic3r/PerimeterGenerator.cpp b/xs/src/libslic3r/PerimeterGenerator.cpp
index cffe14b67..ae3a2088f 100644
--- a/xs/src/libslic3r/PerimeterGenerator.cpp
+++ b/xs/src/libslic3r/PerimeterGenerator.cpp
@@ -2,6 +2,7 @@
 #include "ClipperUtils.hpp"
 #include "ExtrusionEntityCollection.hpp"
 #include <cmath>
+#include <cassert>
 
 namespace Slic3r {