diff --git a/backend/app/api/v1/features.py b/backend/app/api/v1/features.py
index 6fd294e..cab639d 100644
--- a/backend/app/api/v1/features.py
+++ b/backend/app/api/v1/features.py
@@ -206,7 +206,7 @@ async def _load_filter_options(db: AsyncSession) -> dict:
     # 3. nlm_subsets（单次 JOIN + COUNT FILTER，代替 8 次独立查询）
     # 注：code 来自上方 NLM_SUBSET_LABELS 硬编码常量，无注入风险
     subset_filter_cols = ", ".join(
-        f'COUNT(*) FILTER (WHERE j.nlm_subsets @> ARRAY[\'{code}\']) AS "{code}"'
+        f'COUNT(*) FILTER (WHERE j.nlm_subsets @> ARRAY[\'{code}\']::varchar[]) AS "{code}"'
         for code in NLM_SUBSET_LABELS
     )
     subset_row = (await db.execute(text(f"""