diff --git a/app.py b/app.py
index 70520a4..c7c8055 100644
--- a/app.py
+++ b/app.py
@@ -1159,30 +1159,19 @@ def save_pdf_as_webp(file, path):
 
 def get_active_months_query(visible_lists_query=None):
     if db.engine.name in ("sqlite",):
-        month_col = func.strftime("%Y-%m", ShoppingList.created_at)
+        def month_expr(col): return func.strftime("%Y-%m", col)
     elif db.engine.name in ("mysql", "mariadb"):
-        month_col = func.date_format(ShoppingList.created_at, "%Y-%m")
-    else: #PGSQL
-        month_col = func.to_char(ShoppingList.created_at, "YYYY-MM")
-
-    month_col = month_col.label("month")
+        def month_expr(col): return func.date_format(col, "%Y-%m")
+    else:  # PostgreSQL
+        def month_expr(col): return func.to_char(col, "YYYY-MM")
 
     if visible_lists_query is not None:
-        inner = (
-            db.session.query(month_col)
-            .select_from(visible_lists_query.subquery())
-            .filter(month_col.isnot(None))
-            .distinct()
-            .subquery()
-        )
+        s = visible_lists_query.subquery()
+        month_sel = month_expr(s.c.created_at).label("month")
+        inner = db.session.query(month_sel).filter(month_sel.isnot(None)).distinct().subquery()
     else:
-        inner = (
-            db.session.query(month_col)
-            .select_from(ShoppingList)
-            .filter(ShoppingList.created_at.isnot(None))
-            .distinct()
-            .subquery()
-        )
+        month_sel = month_expr(ShoppingList.created_at).label("month")
+        inner = db.session.query(month_sel).filter(ShoppingList.created_at.isnot(None)).distinct().subquery()
 
     rows = db.session.query(inner.c.month).order_by(inner.c.month).all()
     return [r.month for r in rows]