diff --git a/python/swiftest/swiftest/simulation_class.py b/python/swiftest/swiftest/simulation_class.py
index 625d0fae8..54f00a6c8 100644
--- a/python/swiftest/swiftest/simulation_class.py
+++ b/python/swiftest/swiftest/simulation_class.py
@@ -721,9 +721,9 @@ def set_parameter(self, verbose: bool = True, **kwargs):
             "tstart": 0.0,
             "tstop": None,
             "dt": None,
-            "istep_out": None,
+            "istep_out": 1,
             "tstep_out": None,
-            "istep_dump": None,
+            "istep_dump": 1,
             "init_cond_file_type": "NETCDF_DOUBLE",
             "init_cond_file_name": None,
             "init_cond_format": "EL",