diff --git a/equipment/models.py b/equipment/models.py
index a7625be..85d6284 100644
--- a/equipment/models.py
+++ b/equipment/models.py
@@ -98,7 +98,7 @@ class Equipment(EventSpecificMixin, models.Model):
                 )
 
     def ids_aviable(self):
-        res = map(lambda x: x+1, range(self.stock))
+        res = list(map(lambda x: x+1, range(self.stock)))
         for lost in self.losts.all():
             res = [ x
                     for x in res