diff --git a/tests/test_reports_balance.py b/tests/test_reports_balance.py
index 4eafad259855b52aad61d776df1007abf308df1a..8f7e1b97cef0149243e80cf74f5d9ddd2d0e9742 100644
--- a/tests/test_reports_balance.py
+++ b/tests/test_reports_balance.py
@@ -419,10 +419,11 @@ def test_format_sep(sep):
     balance = core.Balance(amounts_from_map(mapping))
     assert balance.format(sep=sep) == expected
 
-def test_format_none():
-    args = (65000, 'BRL')
+@pytest.mark.parametrize('number', [65000, -77000])
+def test_format_none(number):
+    args = (number, 'BRL')
     balance = core.Balance([testutil.Amount(*args)])
-    expected = babel.numbers.format_currency(*args)
+    expected = babel.numbers.format_currency(*args, format_type='accounting')
     assert balance.format(None) == expected
 
 @pytest.mark.parametrize('empty', [