diff --git a/python/swiftest/swiftest/io.py b/python/swiftest/swiftest/io.py
index 64c4dc4a1..ead04cc95 100644
--- a/python/swiftest/swiftest/io.py
+++ b/python/swiftest/swiftest/io.py
@@ -428,6 +428,7 @@ def write_labeled_param(param, param_file_name):
                'TU2S',
                'DU2M',
                'GMTINY',
+               'FRAGMENTATION'
                'MIN_GMFRAG',
                'RESTART']
     ptmp = param.copy()