diff --git a/printing/templates/templates.py b/printing/templates/templates.py
index de5c3eb..59143aa 100644
--- a/printing/templates/templates.py
+++ b/printing/templates/templates.py
@@ -62,6 +62,8 @@ def prise_etat(chbre):
     except Exception as e:
         return style(u"hptools2 failed (%r)" % e, "rouge")
     vlan_list = switch.get_vlans(port)
+    if vlan_list is None:
+        return style(u"vlan_list is empty (hptools failed ?)", "rouge")
 
     vlans = u" " * (13 + len(chbre))
     vlans += u"Vlan%s : " % (u's' if len(vlan_list) > 1 else u"",) + style(u", ".join([unicode(vlan) for vlan in vlan_list]), "orange")