diff --git a/src/libslic3r/SimplifyMeshImpl.hpp b/src/libslic3r/SimplifyMeshImpl.hpp
index 49ecb9ef68..60648168c5 100644
--- a/src/libslic3r/SimplifyMeshImpl.hpp
+++ b/src/libslic3r/SimplifyMeshImpl.hpp
@@ -22,6 +22,7 @@
 #include <type_traits>
 #include <algorithm>
 #include <cmath>
+#include <admesh/stl.h>
 
 #ifndef NDEBUG
 #include <ostream>