diff --git a/src/SMESH/SMESH_MeshEditor.cxx b/src/SMESH/SMESH_MeshEditor.cxx
index 12e01cd2a..d029fe5ca 100644
--- a/src/SMESH/SMESH_MeshEditor.cxx
+++ b/src/SMESH/SMESH_MeshEditor.cxx
@@ -6367,7 +6367,7 @@ SMESH_MeshEditor::Transform (TIDSortedElemSet & theElems,
  *  \param [in] theValue - offset value
  *  \param [out] theTgtMesh - a mesh to add offset elements to
  *  \param [in] theMakeGroups - to generate groups
- *  \return PGroupIDs - IDs of created groups
+ *  \return PGroupIDs - IDs of created groups. NULL means failure
  */
 //================================================================================
 
@@ -6454,6 +6454,8 @@ SMESH_MeshEditor::PGroupIDs SMESH_MeshEditor::Offset( TIDSortedElemSet & theElem
   PGroupIDs newGroupIDs;
   if ( theMakeGroups )
     newGroupIDs = generateGroups( srcNodes, srcElems, "offset", theTgtMesh, false );
+  else
+    newGroupIDs.reset( new std::list< int > );
 
   return newGroupIDs;
 }
diff --git a/src/SMESH_I/SMESH_MeshEditor_i.cxx b/src/SMESH_I/SMESH_MeshEditor_i.cxx
index 1589d11b4..421a0babf 100644
--- a/src/SMESH_I/SMESH_MeshEditor_i.cxx
+++ b/src/SMESH_I/SMESH_MeshEditor_i.cxx
@@ -4115,8 +4115,6 @@ SMESH::SMESH_Mesh_ptr SMESH_MeshEditor_i::Offset( SMESH::SMESH_IDSource_ptr theO
   }
   else
   {
-    theGroups = theCopyGroups ? getGroups( groupIds.get() ) : new SMESH::ListOfGroups;
-
     if ( *theMeshName && mesh_var->NbFaces() == 0 )
     {
       // new mesh empty, remove it
@@ -4126,6 +4124,10 @@ SMESH::SMESH_Mesh_ptr SMESH_MeshEditor_i::Offset( SMESH::SMESH_IDSource_ptr theO
       builder->RemoveObjectWithChildren( meshSO );
       THROW_SALOME_CORBA_EXCEPTION("Offset failed", SALOME::INTERNAL_ERROR);
     }
+    if ( !groupIds ) // nothing changed in the current mesh
+      THROW_SALOME_CORBA_EXCEPTION("Offset failed", SALOME::INTERNAL_ERROR);
+
+    theGroups = theCopyGroups ? getGroups( groupIds.get() ) : new SMESH::ListOfGroups;
 
     // result of Offset() is a tuple (mesh, groups)
     if ( mesh_var->_is_nil() ) pyDump << myMesh_i->_this() << ", ";