diff --git a/tests/conftest.py b/tests/conftest.py
index e9161d77e..2e447c281 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1694,6 +1694,7 @@ def limit_buy_order_old_partial():
         'price': 0.00001099,
         'amount': 90.99181073,
         'filled': 23.0,
+        'cost': 90.99181073 * 23.0,
         'remaining': 67.99181073,
         'status': 'open'
     }