diff --git a/tests/test_fincal.py b/tests/test_fincal.py
index b169040..f45ea64 100644
--- a/tests/test_fincal.py
+++ b/tests/test_fincal.py
@@ -221,3 +221,11 @@ class TestReturns:
         returns1 = ts.calculate_returns("2020-04-10", interval_type='days', interval_value=90, date_format='%Y-%m-%d')
         returns2 = ts.calculate_returns("10-04-2020", interval_type='days', interval_value=90)
         assert round(returns1, 4) == round(returns2, 4) == 5.727
+
+        FincalOptions.date_format = '%m-%d-%Y'
+        with pytest.raises(ValueError):
+            ts.calculate_returns("2020-04-10", compounding=True, interval_type='days', interval_value=90)
+
+        returns1 = ts.calculate_returns("2020-04-10", interval_type='days', interval_value=90, date_format='%Y-%m-%d')
+        returns2 = ts.calculate_returns("04-10-2020", interval_type='days', interval_value=90)
+        assert round(returns1, 4) == round(returns2, 4) == 5.727