diff --git a/bin/osv/osv.py b/bin/osv/osv.py
index d1d7791e9ec..34ac4e469db 100644
--- a/bin/osv/osv.py
+++ b/bin/osv/osv.py
@@ -197,6 +197,14 @@ class osv_memory(osv_base, orm.orm_memory):
     def createInstance(cls, pool, module, cr):       
         parent_names = getattr(cls, '_inherit', None)
         if parent_names:
+            if isinstance(parent_names, (str, unicode)):
+                name = cls._name or parent_name
+                parent_names = [parent_names]
+            else:
+                name = cls._name
+            if not name:
+                raise TypeError('_name is mandatory in case of multiple inheritance')
+
             for parent_name in ((type(parent_names)==list) and parent_names or [parent_names]):
                 parent_class = pool.get(parent_name).__class__
                 assert pool.get(parent_name), "parent class %s does not exist in module %s !" % (parent_name, module)
@@ -208,7 +216,6 @@ class osv_memory(osv_base, orm.orm_memory):
                     else:
                         new.extend(cls.__dict__.get(s, []))
                     nattr[s] = new
-                name = cls._name or cls._inherit
                 cls = type(name, (cls, parent_class), nattr)
 
         obj = object.__new__(cls)
@@ -224,6 +231,14 @@ class osv(osv_base, orm.orm):
     def createInstance(cls, pool, module, cr):
         parent_names = getattr(cls, '_inherit', None)        
         if parent_names:
+            if isinstance(parent_names, (str, unicode)):
+                name = cls._name or parent_name
+                parent_names = [parent_names]
+            else:
+                name = cls._name
+            if not name:
+                raise TypeError('_name is mandatory in case of multiple inheritance')
+
             for parent_name in ((type(parent_names)==list) and parent_names or [parent_names]):
                 parent_class = pool.get(parent_name).__class__
                 assert pool.get(parent_name), "parent class %s does not exist in module %s !" % (parent_name, module)
@@ -246,7 +261,6 @@ class osv(osv_base, orm.orm):
                         else:
                             new.extend(cls.__dict__.get(s, []))
                     nattr[s] = new
-                name = cls._name or cls._inherit
                 cls = type(name, (cls, parent_class), nattr)
         obj = object.__new__(cls)
         obj.__init__(pool, cr)