diff --git a/tcp_tests/managers/rallymanager.py b/tcp_tests/managers/rallymanager.py
index 589e1ee..959ade0 100644
--- a/tcp_tests/managers/rallymanager.py
+++ b/tcp_tests/managers/rallymanager.py
@@ -255,7 +255,7 @@
                 report_prefix,
                 datetime.datetime.now().strftime('%Y%m%d_%H%M%S'))
         else:
-            report_filename = 'report_{1}'.format(
+            report_filename = 'report_{}'.format(
                 datetime.datetime.now().strftime('%Y%m%d_%H%M%S'))
         docker_file_prefix = '/home/rally/.rally/' + report_filename