diff --git a/tools.py b/tools.py
index 31bf27b2..2b13c714 100644
--- a/tools.py
+++ b/tools.py
@@ -212,7 +212,7 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
 
     Keyword argument:
         domain -- YunoHost main domain
-        dyndns -- Subscribe domain to a DynDNS service
+        ignore_dyndns -- Do not subscribe domain to a DynDNS service
         password -- YunoHost admin password
 
     """
@@ -221,6 +221,8 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
     from yunohost.app import app_ssowatconf
     from yunohost.firewall import firewall_upnp, firewall_reload
 
+    dyndns = not ignore_dyndns
+
     try:
         with open('/etc/yunohost/installed') as f: pass
     except IOError: