diff --git a/attributs.py b/attributs.py
index c3e9b41..6bce468 100644
--- a/attributs.py
+++ b/attributs.py
@@ -563,7 +563,7 @@ class ipHostNumber(Attr):
 
     def parse_value(self, ip):
         if ip == '<automatique>':
-            ip = ip4_of_rid(self.parent['rid'][0])
+            ip = ip4_of_rid(str(self.parent['rid'][0]))
         self.value = netaddr.ip.IPAddress(ip)
 
     def __unicode__(self):