diff --git a/Triangulation/include/CGAL/IO/Triangulation_off_ostream.h b/Triangulation/include/CGAL/IO/Triangulation_off_ostream.h
index 49c5dcf6111..7d640156311 100644
--- a/Triangulation/include/CGAL/IO/Triangulation_off_ostream.h
+++ b/Triangulation/include/CGAL/IO/Triangulation_off_ostream.h
@@ -21,6 +21,8 @@
 #ifndef CGAL_TRIANGULATION_IO_H
 #define CGAL_TRIANGULATION_IO_H
 
+#include <CGAL/license/Triangulation.h>
+
 #include <CGAL/Epick_d.h>
 #include <CGAL/Triangulation.h>
 #include <sstream>
diff --git a/Triangulation/include/CGAL/Regular_triangulation.h b/Triangulation/include/CGAL/Regular_triangulation.h
index e4bf206939e..ac1cd942856 100644
--- a/Triangulation/include/CGAL/Regular_triangulation.h
+++ b/Triangulation/include/CGAL/Regular_triangulation.h
@@ -20,6 +20,8 @@
 #ifndef CGAL_REGULAR_TRIANGULATION_H
 #define CGAL_REGULAR_TRIANGULATION_H
 
+#include <CGAL/license/Triangulation.h>
+
 #include <CGAL/Triangulation.h>
 #include <CGAL/Dimension.h>
 #include <CGAL/Default.h>
diff --git a/Triangulation/include/CGAL/Regular_triangulation_traits_adapter.h b/Triangulation/include/CGAL/Regular_triangulation_traits_adapter.h
index e15214a5a03..07a682569ab 100644
--- a/Triangulation/include/CGAL/Regular_triangulation_traits_adapter.h
+++ b/Triangulation/include/CGAL/Regular_triangulation_traits_adapter.h
@@ -20,6 +20,8 @@
 #ifndef CGAL_REGULAR_TRIANGULATION_TRAITS_ADAPTER_H
 #define CGAL_REGULAR_TRIANGULATION_TRAITS_ADAPTER_H
 
+#include <CGAL/license/Triangulation.h>
+
 #include <CGAL/basic.h>
 
 #include <boost/iterator/transform_iterator.hpp>
diff --git a/Triangulation_2/include/CGAL/IO/Triangulation_off_ostream_2.h b/Triangulation_2/include/CGAL/IO/Triangulation_off_ostream_2.h
index a4cd70e8e0d..5590cf94833 100644
--- a/Triangulation_2/include/CGAL/IO/Triangulation_off_ostream_2.h
+++ b/Triangulation_2/include/CGAL/IO/Triangulation_off_ostream_2.h
@@ -21,6 +21,8 @@
 #ifndef CGAL_TRIANGULATION_OFF_OSTREAM_2_H
 #define CGAL_TRIANGULATION_OFF_OSTREAM_2_H
 
+#include <CGAL/license/Triangulation.h>
+
 #include <CGAL/Triangulation_2.h>
 #include <sstream>
 #include <iostream>
diff --git a/Triangulation_3/include/CGAL/IO/Triangulation_off_ostream_3.h b/Triangulation_3/include/CGAL/IO/Triangulation_off_ostream_3.h
index b6287f71d52..db6d34fff7b 100644
--- a/Triangulation_3/include/CGAL/IO/Triangulation_off_ostream_3.h
+++ b/Triangulation_3/include/CGAL/IO/Triangulation_off_ostream_3.h
@@ -21,6 +21,8 @@
 #ifndef CGAL_TRIANGULATION_OFF_OSTREAM_3_H
 #define CGAL_TRIANGULATION_OFF_OSTREAM_3_H
 
+#include <CGAL/license/Triangulation.h>
+
 #include <CGAL/Triangulation_3.h>
 #include <sstream>
 #include <iostream>