diff --git a/freqtrade/persistence/trade_model.py b/freqtrade/persistence/trade_model.py
index 531e86282..7eabfab0f 100644
--- a/freqtrade/persistence/trade_model.py
+++ b/freqtrade/persistence/trade_model.py
@@ -795,10 +795,10 @@ class LocalTrade():
 
         return interest(exchange_name=self.exchange, borrowed=borrowed, rate=rate, hours=hours)
 
-    def _calc_base_close(self, amount: FtPrecise, rate: float, fee: float) -> FtPrecise:
+    def _calc_base_close(self, amount: FtPrecise, rate: float, fee: Optional[float]) -> FtPrecise:
 
         close_trade = amount * FtPrecise(rate)
-        fees = close_trade * FtPrecise(fee)
+        fees = close_trade * FtPrecise(fee or 0.0)
 
         if self.is_short:
             return close_trade + fees