diff --git a/meshmode/dof_array.py b/meshmode/dof_array.py
index b26732c3d6d7d9b54313fbde8d882998459b37d1..c77fdd0f75774cb9ce8f4ee3df88a100d9842e4b 100644
--- a/meshmode/dof_array.py
+++ b/meshmode/dof_array.py
@@ -195,7 +195,7 @@ def flatten(ary: np.ndarray) -> np.ndarray:
     def prg():
         return make_loopy_program(
             "{[iel,idof]: 0<=iel<nelements and 0<=idof<ndofs_per_element}",
-            "result[grp_start + iel*nunit_dofs + idof] = grp_ary[iel, idof]",
+            "result[grp_start + iel*ndofs_per_element + idof] = grp_ary[iel, idof]",  # noqa
             name="flatten")
 
     result = actx.empty(group_starts[-1], dtype=ary.entry_dtype)