diff --git a/applications/utilities/mesh/manipulation/mergeMeshes/mergePolyMesh.C b/applications/utilities/mesh/manipulation/mergeMeshes/mergePolyMesh.C
index 37ad24cad9..3331324800 100644
--- a/applications/utilities/mesh/manipulation/mergeMeshes/mergePolyMesh.C
+++ b/applications/utilities/mesh/manipulation/mergeMeshes/mergePolyMesh.C
@@ -273,6 +273,7 @@ void Foam::mergePolyMesh::addMesh(const polyMesh& m)
     forAll(fz, zonei)
     {
         faceZoneIndices[zonei] = zoneIndex(faceZoneNames_, fz[zonei].name());
+        faceZonesAddedFaces_.setSize(faceZoneNames_.size());
     }
 
     const faceList& f = m.faces();