diff --git a/Hash_map/include/CGAL/Hash_map/internal/chained_map.h b/Hash_map/include/CGAL/Hash_map/internal/chained_map.h
index 729e2a58092..de33fbc6c6b 100644
--- a/Hash_map/include/CGAL/Hash_map/internal/chained_map.h
+++ b/Hash_map/include/CGAL/Hash_map/internal/chained_map.h
@@ -17,6 +17,7 @@
 #define CGAL_HASH_MAP_INTERNAL_CHAINED_MAP_H
 
 #include <CGAL/memory.h>
+#inclue <CGAL/assertions.h>
 #include <iostream>
 #include <limits>