diff --git a/aviary/core/aviary_group.py b/aviary/core/aviary_group.py
index 403fc0067..888b8bce9 100644
--- a/aviary/core/aviary_group.py
+++ b/aviary/core/aviary_group.py
@@ -734,7 +734,7 @@ def add_subsystem_timeseries_outputs(phase, phase_name):
                     aviary_inputs=self.aviary_inputs,
                     **kwargs,
                 )
-                for parameter in parameter_dict:
+                for parameter in sorted(parameter_dict):
                     external_parameters[phase_name][parameter] = parameter_dict[parameter]
 
         traj = setup_trajectory_params(