diff --git a/api/routers/state.py b/api/routers/state.py
index 28ab4c2..215305b 100644
--- a/api/routers/state.py
+++ b/api/routers/state.py
@@ -339,11 +339,12 @@ async def _derive_next_steps(session: AsyncSession) -> list[NextStep]:
         if task.id in seen_task_ids:
             continue
         domain_slug = await _get_domain_slug_for_workstream(from_ws, session)
-        blocker_slugs = ", ".join(
-            (await session.get(Workstream, tid)).slug
-            for tid in to_ws_ids
-            if await session.get(Workstream, tid)
-        )
+        _blocker_slugs = []
+        for tid in to_ws_ids:
+            _ws = await session.get(Workstream, tid)
+            if _ws:
+                _blocker_slugs.append(_ws.slug)
+        blocker_slugs = ", ".join(_blocker_slugs)
         steps.append(NextStep(
             type="dependency_cleared",
             domain=domain_slug,