diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.C b/src/OpenFOAM/containers/Lists/ListOps/ListOps.C
index fc78d43f1a..5f6d2a04d5 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.C
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.C
@@ -160,7 +160,7 @@ void Foam::inplaceReorder
 }
 
 
-void Foam::ListOps::identity(labelList& map, label start)
+void Foam::ListOps::identity(labelUList& map, label start)
 {
     std::iota(map.begin(), map.end(), start);
 }
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
index 8fd5b87bc6..224a1c6223 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
@@ -586,7 +586,7 @@ struct greater
 
 //- Set identity map with (map[i] == i)
 //  Optionally with an alternative start index, so that (map[i] == i+start)
-void identity(labelList& map, label start=0);
+void identity(labelUList& map, label start=0);
 
 
 //- Find index of the first occurrence that satisfies the predicate.