diff --git a/freqtrade/optimize/backtesting.py b/freqtrade/optimize/backtesting.py
index 0605799b1..d5039fe7d 100644
--- a/freqtrade/optimize/backtesting.py
+++ b/freqtrade/optimize/backtesting.py
@@ -159,7 +159,8 @@ class Backtesting(object):
                                       profit_abs=trade.calc_profit(rate=sell_row.open),
                                       open_time=buy_row.date,
                                       close_time=sell_row.date,
-                                      trade_duration=(sell_row.date - buy_row.date).total_seconds() // 60,
+                                      trade_duration=int((
+                                          sell_row.date - buy_row.date).total_seconds() // 60),
                                       open_index=buy_row.Index,
                                       close_index=sell_row.Index,
                                       open_at_end=False,
@@ -174,7 +175,8 @@ class Backtesting(object):
                                  profit_abs=trade.calc_profit(rate=sell_row.open),
                                  open_time=buy_row.date,
                                  close_time=sell_row.date,
-                                 trade_duration=(sell_row.date - buy_row.date).total_seconds() // 60,
+                                 trade_duration=int((
+                                     sell_row.date - buy_row.date).total_seconds() // 60),
                                  open_index=buy_row.Index,
                                  close_index=sell_row.Index,
                                  open_at_end=True,