diff --git a/python/dune/codegen/blockstructured/vectorization.py b/python/dune/codegen/blockstructured/vectorization.py
index c78ae24fa4acca4751332f2a13be0d71dc0af18f..681551ca3684400efaf2b046e290b74b5a655bd4 100644
--- a/python/dune/codegen/blockstructured/vectorization.py
+++ b/python/dune/codegen/blockstructured/vectorization.py
@@ -58,7 +58,7 @@ def add_vcl_accum_insns(knl, inner_iname, outer_iname, vcl_size):
             expr_without_r = prim.Sum(tuple(e for e in insn.expression.children if not e == insn.assignee))
 
             inames_micro = set((i for i in insn.within_inames if i.startswith('micro')))
-            iname_ix = next((i for i in inames_micro if '_x' in i))
+            iname_ix = next((i for i in inames_micro if '_x' in i))  # TODO use TaggedIname when available
 
             # need inames for head and tail handling a priori
             from loopy.match import Not, All