diff --git a/python/dune/codegen/sumfact/autotune.py b/python/dune/codegen/sumfact/autotune.py
index f8b03de6a84388323ce708a0372b6d7a425d7608..6273e355988ebc1a474251aed06291bc5ba81564 100644
--- a/python/dune/codegen/sumfact/autotune.py
+++ b/python/dune/codegen/sumfact/autotune.py
@@ -231,6 +231,7 @@ def generate_standalone_code(sf, filename):
     # Extract sum factorization kernel
     from dune.codegen.pdelab.localoperator import extract_kernel_from_cache
     knl = realize_sumfact_kernel_function(sf)
+    first_line = knl.member.lines[0]
 
     with open(filename, "w") as f:
         f.writelines(["// {}".format(first_line),