diff --git a/src/meshio/dolfin/_dolfin.py b/src/meshio/dolfin/_dolfin.py
index e43dbd54..39c2238b 100644
--- a/src/meshio/dolfin/_dolfin.py
+++ b/src/meshio/dolfin/_dolfin.py
@@ -207,7 +207,7 @@ def _write_cell_data(filename, dim, cell_data):
     )
 
     for k, value in enumerate(cell_data):
-        ET.SubElement(mesh_function, "entity", index=str(k), value=repr(value))
+        ET.SubElement(mesh_function, "entity", index=str(k), value=repr(value.item()))
 
     tree = ET.ElementTree(dolfin)
     tree.write(filename)