diff --git a/Stream_support/include/CGAL/IO/File_scanner_OFF.h b/Stream_support/include/CGAL/IO/File_scanner_OFF.h
index c05febd95cf..f43aab14edf 100644
--- a/Stream_support/include/CGAL/IO/File_scanner_OFF.h
+++ b/Stream_support/include/CGAL/IO/File_scanner_OFF.h
@@ -376,7 +376,7 @@ public:
 
   void skip_to_next_vertex( std::size_t current_vertex);
 
-  void scan_facet( std::size_t& size, int CGAL_assertion_code(current_facet)) {
+  void scan_facet( std::size_t& size, std::size_t CGAL_assertion_code(current_facet)) {
         CGAL_assertion( current_facet < size_of_facets());
         if ( binary()){
           Integer32 i32;
diff --git a/Stream_support/include/CGAL/IO/generic_copy_OFF.h b/Stream_support/include/CGAL/IO/generic_copy_OFF.h
index 0b26e297c47..47cb4f7eba6 100644
--- a/Stream_support/include/CGAL/IO/generic_copy_OFF.h
+++ b/Stream_support/include/CGAL/IO/generic_copy_OFF.h
@@ -72,11 +72,11 @@ generic_copy_OFF( File_scanner_OFF& scanner,
     for ( i = 0; i < scanner.size_of_facets(); i++) {
         if ( ! in)
             return;
-        Integer32 no;
+        std::size_t no;
         scanner.scan_facet( no, i);
         writer.write_facet_begin( no);
         for ( int j = 0; j < no; j++) {
-            Integer32 index;
+          std::size_t index;
             scanner.scan_facet_vertex_index( index, i);
             writer.write_facet_vertex_index( index);
         }