diff --git a/docs/strategy-callbacks.md b/docs/strategy-callbacks.md
index a06e76454..f4ad109d5 100644
--- a/docs/strategy-callbacks.md
+++ b/docs/strategy-callbacks.md
@@ -654,6 +654,7 @@ class DigDeeperStrategy(IStrategy):
         if last_candle['close'] < previous_candle['close']:
             return None
 
+        filled_buys = trade.select_filled_orders('buy')
         count_of_buys = trade.nr_of_successful_buys
         # Allow up to 3 additional increasingly larger buys (4 in total)
         # Initial buy is 1x