diff -r e343594c0014 -r 4cad934aa9ce config.py
--- a/config.py	Fri Jan 19 10:41:01 2018 +0000
+++ b/config.py	Fri Jan 19 14:42:27 2018 +0000
@@ -23,6 +23,7 @@
        'executable': 'borg',
        'common_parameters': [],
        'create_parameters': [],
+       'prune_parameters': [],
     }
 }
 
@@ -128,12 +129,16 @@
         cfg[field]=fn(cfg, field, field, loc, defa[field])
         return cfg
 
+    def check_parameters(cmd):
+        settings['borg']=check_and_set(settings['borg'], cmd+'_parameters',
+                                       'borg', defaults['borg'],
+                                       check_list_of_dicts)
+
     settings['borg']=check_and_set(settings['borg'], 'executable', 'borg',
                                    defaults['borg'], check_string)
 
-    settings['borg']=check_and_set(settings['borg'], 'common_parameters', 'borg',
-                                   defaults['borg'], check_list_of_dicts)
+    check_parameters('common')
+    check_parameters('create')
+    check_parameters('prune')
 
-    settings['borg']=check_and_set(settings['borg'], 'create_parameters', 'borg',
-                                   defaults['borg'], check_list_of_dicts)