diff --git a/bundles/dovecot/metadata.py b/bundles/dovecot/metadata.py
index c51a93c..f87a9c2 100644
--- a/bundles/dovecot/metadata.py
+++ b/bundles/dovecot/metadata.py
@@ -74,10 +74,10 @@ def iptables(metadata):
         'iptables': {
             'port_rules': {
                 # imap(s)
-                '143': atomic(metadata.get('dovecot/restrict-to', set('*'))),
-                '993': atomic(metadata.get('dovecot/restrict-to', set('*'))),
+                '143': atomic(metadata.get('dovecot/restrict-to', {'*'})),
+                '993': atomic(metadata.get('dovecot/restrict-to', {'*'})),
                 # managesieve
-                '4190': atomic(metadata.get('dovecot/restrict-to', set('*'))),
+                '4190': atomic(metadata.get('dovecot/restrict-to', {'*'})),
             },
         },
     }
diff --git a/bundles/kodi/metadata.py b/bundles/kodi/metadata.py
index 8807b21..0d888f9 100644
--- a/bundles/kodi/metadata.py
+++ b/bundles/kodi/metadata.py
@@ -50,7 +50,7 @@ def iptables(metadata):
     return {
         'iptables': {
             'port_rules': {
-                '8080': atomic(metadata.get('kodi/restrict-to', set('*'))),
+                '8080': atomic(metadata.get('kodi/restrict-to', {'*'})),
             },
         },
     }
diff --git a/bundles/nginx/metadata.py b/bundles/nginx/metadata.py
index 2402abc..1e0f238 100644
--- a/bundles/nginx/metadata.py
+++ b/bundles/nginx/metadata.py
@@ -159,8 +159,8 @@ def iptables(metadata):
     return {
         'iptables': {
             'port_rules': {
-                '80': atomic(metadata.get('nginx/restrict-to', set('*'))),
-                '443': atomic(metadata.get('nginx/restrict-to', set('*'))),
+                '80': atomic(metadata.get('nginx/restrict-to', {'*'})),
+                '443': atomic(metadata.get('nginx/restrict-to', {'*'})),
             },
         },
     }
diff --git a/bundles/oidentd/metadata.py b/bundles/oidentd/metadata.py
index d17952e..5d997b4 100644
--- a/bundles/oidentd/metadata.py
+++ b/bundles/oidentd/metadata.py
@@ -16,7 +16,7 @@ def iptables(metadata):
     return {
         'iptables': {
             'port_rules': {
-                '113': atomic(metadata.get('oidentd/restrict-to', set('*'))),
+                '113': atomic(metadata.get('oidentd/restrict-to', {'*'})),
             },
         },
     }
diff --git a/bundles/openssh/metadata.py b/bundles/openssh/metadata.py
index ebc8854..a7a8424 100644
--- a/bundles/openssh/metadata.py
+++ b/bundles/openssh/metadata.py
@@ -22,7 +22,7 @@ def iptables(metadata):
     return {
         'iptables': {
             'port_rules': {
-                '22': atomic(metadata.get('openssh/restrict-to', set('*'))),
+                '22': atomic(metadata.get('openssh/restrict-to', {'*'})),
             },
         },
     }
diff --git a/bundles/postfix/metadata.py b/bundles/postfix/metadata.py
index ffdf6f6..f54ce30 100644
--- a/bundles/postfix/metadata.py
+++ b/bundles/postfix/metadata.py
@@ -77,7 +77,7 @@ def letsencrypt(metadata):
 )
 def iptables(metadata):
     if node.has_bundle('postfixadmin'):
-        default = set('*')
+        default = {'*'}
     else:
         default = metadata.get('postfix/mynetworks', set())
 
diff --git a/bundles/powerdns/metadata.py b/bundles/powerdns/metadata.py
index c791d26..99ba6a1 100644
--- a/bundles/powerdns/metadata.py
+++ b/bundles/powerdns/metadata.py
@@ -176,8 +176,8 @@ def iptables(metadata):
     return {
         'iptables': {
             'port_rules': {
-                '53': atomic(metadata.get('powerdns/restrict-to', set('*'))),
-                '53/udp': atomic(metadata.get('powerdns/restrict-to', set('*'))),
+                '53': atomic(metadata.get('powerdns/restrict-to', {'*'})),
+                '53/udp': atomic(metadata.get('powerdns/restrict-to', {'*'})),
             },
         },
     }
diff --git a/bundles/transmission/metadata.py b/bundles/transmission/metadata.py
index dfe8d68..cc29ccf 100644
--- a/bundles/transmission/metadata.py
+++ b/bundles/transmission/metadata.py
@@ -42,9 +42,9 @@ def iptables(metadata):
     return {
         'iptables': {
             'port_rules': {
-                str(metadata.get('transmission/config/peer-port')): set('*'),
-                str(metadata.get('transmission/config/peer-port')) + '/udp': set('*'),
-                str(metadata.get('transmission/config/rpc-port')): atomic(metadata.get('transmission/restrict-to', set('*'))),
+                str(metadata.get('transmission/config/peer-port')): atomic({'*'}),
+                str(metadata.get('transmission/config/peer-port')) + '/udp': atomic({'*'}),
+                str(metadata.get('transmission/config/rpc-port')): atomic(metadata.get('transmission/restrict-to', {'*'})),
             },
         },
     }