diff --git a/Surface_mesher/include/CGAL/IO/facets_in_complex_2_to_triangle_mesh.h b/Surface_mesher/include/CGAL/IO/facets_in_complex_2_to_triangle_mesh.h
index db78a6bb947..80a3afaefe5 100644
--- a/Surface_mesher/include/CGAL/IO/facets_in_complex_2_to_triangle_mesh.h
+++ b/Surface_mesher/include/CGAL/IO/facets_in_complex_2_to_triangle_mesh.h
@@ -19,6 +19,7 @@
 
 #include <CGAL/boost/graph/Euler_operations.h>
 #include <unordered_map>
+#include <set>
 #include <stack>
 
 namespace CGAL{