diff --git a/attributes/postfix.rb b/attributes/postfix.rb
index d9ff0e3..afdeb7c 100644
--- a/attributes/postfix.rb
+++ b/attributes/postfix.rb
@@ -1,17 +1,17 @@
-default[:postfix][:mail_type]  = "client"
-default[:postfix][:myhostname] = fqdn
-default[:postfix][:mydomain]   = domain
-default[:postfix][:myorigin]   = "$myhostname"
-default[:postfix][:relayhost]  = ""
-default[:postfix][:mail_relay_networks] = "127.0.0.0/8"
+set_unless[:postfix][:mail_type]  = "client"
+set_unless[:postfix][:myhostname] = fqdn
+set_unless[:postfix][:mydomain]   = domain
+set_unless[:postfix][:myorigin]   = "$myhostname"
+set_unless[:postfix][:relayhost]  = ""
+set_unless[:postfix][:mail_relay_networks] = "127.0.0.0/8"
 
-default[:postfix][:smtp_sasl_auth_enable] = "no"
+set_unless[:postfix][:smtp_sasl_auth_enable] = "no"
 
 if postfix[:smtp_sasl_auth_enable] == "yes"
-  default[:postfix][:smtp_sasl_password_maps]    = "hash:/etc/postfix/sasl_passwd"
-  default[:postfix][:smtp_sasl_security_options] = "noanonymous"
-  default[:postfix][:smtp_tls_cafile] = "/etc/postfix/cacert.pem"
-  default[:postfix][:smtp_use_tls]    = "yes"
-  default[:postfix][:smtp_sasl_user_name] = ""
-  default[:postfix][:smtp_sasl_passwd]    = ""
+  set_unless[:postfix][:smtp_sasl_password_maps]    = "hash:/etc/postfix/sasl_passwd"
+  set_unless[:postfix][:smtp_sasl_security_options] = "noanonymous"
+  set_unless[:postfix][:smtp_tls_cafile] = "/etc/postfix/cacert.pem"
+  set_unless[:postfix][:smtp_use_tls]    = "yes"
+  set_unless[:postfix][:smtp_sasl_user_name] = ""
+  set_unless[:postfix][:smtp_sasl_passwd]    = ""
 end