diff --git a/focker.py b/focker.py
index 3d31467..e4f41e4 100644
--- a/focker.py
+++ b/focker.py
@@ -18,7 +18,8 @@ from .zfs import zfs_init
 from .jail import command_jail_run, \
     command_jail_list, \
     command_jail_tag, \
-    command_jail_untag
+    command_jail_untag, \
+    command_jail_prune
 
 
 def create_parser():
@@ -75,6 +76,9 @@ def create_parser():
     parser.set_defaults(func=command_jail_untag)
     parser.add_argument('tags', type=str, nargs='+')
 
+    parser = subparsers.add_parser('prune')
+    parser.set_defaults(func=command_jail_prune)
+
     # volume
     subparsers = subparsers_top.add_parser('volume').add_subparsers()
     parser = subparsers.add_parser('create')
diff --git a/jail.py b/jail.py
index 153bddd..81c575e 100644
--- a/jail.py
+++ b/jail.py
@@ -56,6 +56,10 @@ def jail_run(path, command, mounts=[]):
         raise RuntimeError('Command failed')
 
 
+def jail_remove(path):
+    print('Removing jail:', path)
+
+
 def command_jail_run(args):
     base, _ = zfs_snapshot_by_tag_or_sha256(args.image)
     # root = '/'.join(base.split('/')[:-1])
@@ -95,3 +99,15 @@ def command_jail_tag(args):
 
 def command_jail_untag(args):
     zfs_untag(args.tags, focker_type='jail')
+
+
+def command_jail_prune(args):
+    jails = subprocess.check_output(['jls', '--libxo=json'])
+    jails = json.loads(jails)['jail-information']['jail']
+    used = set()
+    for j in jails:
+        used.add(j['path'])
+    lst = zfs_list(fields=['focker:sha256,focker:tags,mountpoint,name'], focker_type='jail')
+    for j in lst:
+        if j[1] == '-' and j[2] not in used:
+            jail_remove(j[3])