diff --git a/erpnext/stock/report/stock_balance/stock_balance.py b/erpnext/stock/report/stock_balance/stock_balance.py
index 5a3e8911fcf..7c77c81e58f 100644
--- a/erpnext/stock/report/stock_balance/stock_balance.py
+++ b/erpnext/stock/report/stock_balance/stock_balance.py
@@ -614,7 +614,11 @@ class StockBalanceReport:
 			return
 
 		bal_qty_idx = next(
-			(i for i, col in enumerate(self.columns) if isinstance(col, dict) and col.get("fieldname") == "bal_qty"),
+			(
+				i
+				for i, col in enumerate(self.columns)
+				if isinstance(col, dict) and col.get("fieldname") == "bal_qty"
+			),
 			None,
 		)
 		if bal_qty_idx is None:
diff --git a/erpnext/stock/report/stock_balance/test_stock_balance.py b/erpnext/stock/report/stock_balance/test_stock_balance.py
index 16ecb971620..2a504f637e0 100644
--- a/erpnext/stock/report/stock_balance/test_stock_balance.py
+++ b/erpnext/stock/report/stock_balance/test_stock_balance.py
@@ -202,6 +202,7 @@ class TestStockBalance(ERPNextTestSuite):
 
 	def test_alt_uom_balance_uses_first_alternate_uom(self):
 		"""When an item has multiple alt UOMs, only the first (lowest idx) is shown."""
+		frappe.get_doc({"doctype": "UOM", "uom_name": "Carton"}).insert(ignore_if_duplicate=True)
 		self.item.append("uoms", {"conversion_factor": 12, "uom": "Box"})
 		self.item.append("uoms", {"conversion_factor": 144, "uom": "Carton"})
 		self.item.save()