diff --git a/degiroapi/__init__.py b/degiroapi/__init__.py
index c26e1a1..6769d2f 100644
--- a/degiroapi/__init__.py
+++ b/degiroapi/__init__.py
@@ -120,7 +120,7 @@ def transactions(self, from_date, to_date, group_transactions=False):
         transactions_payload = {
             'fromDate': from_date.strftime('%d/%m/%Y'),
             'toDate': to_date.strftime('%d/%m/%Y'),
-            'group_transactions_by_order': group_transactions,
+            'groupTransactionsByOrder': group_transactions,
             'intAccount': self.client_info.account_id,
             'sessionId': self.session_id
         }