diff --git a/STL_Extension/include/CGAL/Handle.h b/STL_Extension/include/CGAL/Handle.h
index 55634481044..dd0d5f42576 100644
--- a/STL_Extension/include/CGAL/Handle.h
+++ b/STL_Extension/include/CGAL/Handle.h
@@ -18,6 +18,7 @@
 #define CGAL_HANDLE_H
 
 #include <cstddef>
+#include <cstdint>
 #include <atomic>
 #include <CGAL/Handle_for.h>
 #include <CGAL/assertions.h>