diff --git a/loopy/schedule/__init__.py b/loopy/schedule/__init__.py
index 234ca95a9a51891d437c6fa0c7de7d5fc410db47..063d0ef0a3432da789aab90265336918f5ca5c83 100644
--- a/loopy/schedule/__init__.py
+++ b/loopy/schedule/__init__.py
@@ -142,7 +142,7 @@ def generate_sub_sched_items(schedule, start_idx):
 def get_insn_ids_for_block_at(schedule, start_idx):
     return frozenset(
             sub_sched_item.insn_id
-            for sub_sched_item in generate_sub_sched_items(
+            for i, sub_sched_item in generate_sub_sched_items(
                 schedule, start_idx)
             if isinstance(sub_sched_item, RunInstruction))