diff --git a/docs/strategy-advanced.md b/docs/strategy-advanced.md
index 7fa824a5b..96c927965 100644
--- a/docs/strategy-advanced.md
+++ b/docs/strategy-advanced.md
@@ -57,7 +57,7 @@ class AwesomeStrategy(IStrategy):
         dataframe['atr'] = ta.ATR(dataframe)
         if self.dp.runmode.value in ('backtest', 'hyperopt'):
           # add indicator mapped to correct DatetimeIndex to custom_info
-          self.custom_info[metadata['pair']] = dataframe[['date', 'atr']].copy().set_index('date')
+          self.custom_info[metadata['pair']] = dataframe[['date', 'atr']].set_index('date')
         return dataframe
 ```