diff --git a/freqtrade/optimize/hyperopt_loss/hyperopt_loss_sortino_daily.py b/freqtrade/optimize/hyperopt_loss/hyperopt_loss_sortino_daily.py
index f5fe4590e..5beacc6fc 100644
--- a/freqtrade/optimize/hyperopt_loss/hyperopt_loss_sortino_daily.py
+++ b/freqtrade/optimize/hyperopt_loss/hyperopt_loss_sortino_daily.py
@@ -52,7 +52,7 @@ class SortinoHyperOptLossDaily(IHyperOptLoss):
         total_profit = sum_daily["profit_ratio_after_slippage"] - minimum_acceptable_return
         expected_returns_mean = total_profit.mean()
 
-        sum_daily['downside_returns'] = 0
+        sum_daily['downside_returns'] = 0.0
         sum_daily.loc[total_profit < 0, 'downside_returns'] = total_profit
         total_downside = sum_daily['downside_returns']
         # Here total_downside contains min(0, P - MAR) values,