diff --git a/BGL/include/CGAL/boost/graph/METIS/partition_dual_graph.h b/BGL/include/CGAL/boost/graph/METIS/partition_dual_graph.h
index ce82306e85e..69e31c2eb95 100644
--- a/BGL/include/CGAL/boost/graph/METIS/partition_dual_graph.h
+++ b/BGL/include/CGAL/boost/graph/METIS/partition_dual_graph.h
@@ -79,6 +79,7 @@ void partition_dual_graph(const TriangleMesh& tm,
 
   // a dual edge between elements exists if they share 'nparts' vertices
   idx_t ncommon = 2;
+  idx_t nparts_as_idx_t = nparts;
 
   // either the edgecut or the total communication volume of the dual graph’s partitioning
   idx_t objval;
@@ -98,7 +99,7 @@ void partition_dual_graph(const TriangleMesh& tm,
   CGAL_assertion_code(int ret =)
     METIS_PartMeshDual(&ne, &nn, eptr, eind,
                        nullptr /* elements weights*/, nullptr /*elements sizes*/,
-                       &ncommon, &nparts,
+                       &ncommon, &nparts_as_idx_t,
                        nullptr /* partitions weights */,
                        *options,
                        &objval, epart, npart);
diff --git a/BGL/include/CGAL/boost/graph/METIS/partition_graph.h b/BGL/include/CGAL/boost/graph/METIS/partition_graph.h
index c95a8fb7efb..ae1058c3917 100644
--- a/BGL/include/CGAL/boost/graph/METIS/partition_graph.h
+++ b/BGL/include/CGAL/boost/graph/METIS/partition_graph.h
@@ -112,6 +112,8 @@ void partition_graph(const TriangleMesh& tm,
     eptr[i + 1] = j;
   }
 
+  idx_t nparts_as_idx_t = nparts;
+
   // either the edgecut or the total communication volume of the dual graph’s partitioning
   idx_t objval;
 
@@ -130,7 +132,7 @@ void partition_graph(const TriangleMesh& tm,
   CGAL_assertion_code(int ret =)
     METIS_PartMeshNodal(&ne, &nn, eptr, eind,
                         nullptr /* nodes weights */, nullptr /* nodes sizes */,
-                        &nparts,
+                        &nparts_as_idx_t,
                         nullptr /* partitions weights */,
                         *options,
                         &objval, epart, npart);