diff --git a/freqtrade/optimize/backtesting.py b/freqtrade/optimize/backtesting.py
index 2b7e048bd..ee85ac711 100644
--- a/freqtrade/optimize/backtesting.py
+++ b/freqtrade/optimize/backtesting.py
@@ -136,8 +136,13 @@ class Backtesting:
             self.fee = config['fee']
             logger.info(f"Using fee {self.fee:.4%} from config.")
         else:
-            fees = [self.exchange.get_fee(symbol=self.pairlists.whitelist[0], taker_or_maker=mot)
-                    for mot in ('taker', 'maker')]
+            fees = [
+                self.exchange.get_fee(
+                    symbol=self.pairlists.whitelist[0],
+                    taker_or_maker=mt,  # type: ignore
+                    )
+                for mt in ('taker', 'maker')
+            ]
             self.fee = max(fee for fee in fees if fee is not None)
             logger.info(f"Using fee {self.fee:.4%} - worst case fee from exchange (lowest tier).")
         self.precision_mode = self.exchange.precisionMode