diff --git a/Tetrahedral_remeshing/examples/Tetrahedral_remeshing/tetrahedral_remeshing_io.h b/Tetrahedral_remeshing/examples/Tetrahedral_remeshing/tetrahedral_remeshing_io.h
index e052780e7fb..e42f07740ff 100644
--- a/Tetrahedral_remeshing/examples/Tetrahedral_remeshing/tetrahedral_remeshing_io.h
+++ b/Tetrahedral_remeshing/examples/Tetrahedral_remeshing/tetrahedral_remeshing_io.h
@@ -36,6 +36,9 @@ bool save_binary_triangulation(std::ostream& os, const T3& t3)
 template<typename T3>
 void save_ascii_triangulation(const char* filename, const T3& t3)
 {
+  if (!t3.is_valid(true))
+    std::cerr << "Invalid triangulation!" << std::endl;
+
   CGAL::Tetrahedral_remeshing::debug::dump_triangulation_cells(
         t3, filename);
 }