diff --git a/VTUinterface/vtuIO.py b/VTUinterface/vtuIO.py
index bfc978b..9f38737 100644
--- a/VTUinterface/vtuIO.py
+++ b/VTUinterface/vtuIO.py
@@ -705,7 +705,7 @@ def add_cell_field(self, field, fieldname, ofilename, writefile=True, array_type
         array_type : `vtk array type`
         datamode : `str`
         """
-        field_vtk = numpy_to_vtk(field)
+        field_vtk = numpy_to_vtk(field, array_type=array_type)
         r = self.cdata.AddArray(field_vtk)
         self.cdata.GetArray(r).SetName(fieldname)
         if writefile is True: