diff --git a/process/main.py b/process/main.py
index ad766c609f..2c1937cf57 100644
--- a/process/main.py
+++ b/process/main.py
@@ -427,8 +427,15 @@ def set_mfile(self):
     def initialise():
         """Run the init module to call all initialisation routines."""
         initialise_imprad()
+        # Reads in input file
         fortran.init_module.init()
 
+        # Order optimisation parameters (arbitrary order in input file)
+        # Ensures consistency and makes output comparisons more straightforward
+        n = int(fortran.numerics.nvar)
+        # [:n] as array always at max size: contains 0s
+        fortran.numerics.ixc[:n].sort()
+
     def run_tests(self):
         """Run tests if required to by input file."""
         # TODO This would do better in a separate input validation module.