diff --git a/lib/backend.py b/lib/backend.py
index d63edfe50b48d1fe4eb320907a00532cabedc27d..bb5bfe04812f3a53989e2f85aaea1b72262f49dc 100644
--- a/lib/backend.py
+++ b/lib/backend.py
@@ -995,14 +995,11 @@ def _OSOndiskVersion(name, os_dir):
 def DiagnoseOS(top_dirs=None):
   """Compute the validity for all OSes.
 
-  For each name in all the given top directories (if not given defaults
-  to constants.OS_SEARCH_PATH) it will return an object. If this is a valid
-  os, the object will be an instance of the object.OS class. If not,
-  it will be an instance of errors.InvalidOS and this signifies that
-  this name does not correspond to a valid OS.
+  Returns an OS object for each name in all the given top directories
+  (if not given defaults to constants.OS_SEARCH_PATH)
 
   Returns:
-    list of objects
+    list of OS objects
 
   """
   if top_dirs is None:
@@ -1021,7 +1018,7 @@ def DiagnoseOS(top_dirs=None):
           os_inst = OSFromDisk(name, base_dir=dir)
           result.append(os_inst)
         except errors.InvalidOS, err:
-          result.append(err)
+          result.append(objects.OS.FromInvalidOS(err))
 
   return result
 
@@ -1075,7 +1072,7 @@ def OSFromDisk(name, base_dir=None):
                              script)
 
 
-  return objects.OS(name=name, path=os_dir,
+  return objects.OS(name=name, path=os_dir, status=constants.OS_VALID_STATUS,
                     create_script=os_scripts['create'],
                     export_script=os_scripts['export'],
                     import_script=os_scripts['import'],
diff --git a/scripts/gnt-os b/scripts/gnt-os
index d6f7210bcc40c93337bb1cfb0af5d474d68e932e..5918769eb55925f6ea6657a61679406f96cb16d0 100755
--- a/scripts/gnt-os
+++ b/scripts/gnt-os
@@ -30,72 +30,6 @@ from ganeti import utils
 from ganeti import errors
 
 
-def _DiagnoseOSValid(obj):
-  """Verify whether an OS diagnose object represents a valid OS
-
-    Args:
-      obj: an diagnostic object as returned by OpDiagnoseOS
-
-    Returns:
-      bool: OS validity status
-
-  """
-  if isinstance(obj, objects.OS):
-    return True
-  elif isinstance(obj, errors.InvalidOS):
-    return False
-  else:
-    raise errors.ProgrammerError("unknown OS diagnose type: '%s'" % type(obj))
-
-
-def _DiagnoseOSName(obj):
-  """Generate a status message for an OS diagnose object.
-
-    Args:
-      obj: an diagnostic object as returned by OpDiagnoseOS
-
-    Returns:
-      string: the name of the OS in question
-
-  """
-  if _DiagnoseOSValid(obj):
-    return obj.name
-  else:
-    return obj.args[0]
-
-
-def _DiagnoseOSStatus(obj):
-  """Generate a status message for an OS diagnose object.
-
-    Args:
-      obj: an diagnostic object as returned by OpDiagnoseOS
-
-    Returns:
-      string: a description of the OS status
-
-  """
-  if _DiagnoseOSValid(obj):
-    return "valid"
-  else:
-    return obj.args[2]
-
-
-def _DiagnoseOSPath(obj):
-  """Get the path out of an OS diagnose object.
-
-    Args:
-      obj: an diagnostic object as returned by OpDiagnoseOS
-
-    Returns:
-      string: the OS path
-
-  """
-  if _DiagnoseOSValid(obj):
-    return obj.path
-  else:
-    return obj.args[1]
-
-
 def _DiagnoseByOS(rlist):
   """Remap an OpDiagnoseOS() return list into an a per-os per-node dictionary
 
@@ -112,13 +46,12 @@ def _DiagnoseByOS(rlist):
   for node_name, nr in rlist.iteritems():
     if not nr:
       continue
-    for obj in nr:
-      os_name = _DiagnoseOSName(obj)
-      if os_name not in all_os:
-        all_os[os_name] = {}
-      if node_name not in all_os[os_name]:
-        all_os[os_name][node_name] = []
-      all_os[os_name][node_name].append(obj)
+    for os in nr:
+      if os.name not in all_os:
+        all_os[os.name] = {}
+      if node_name not in all_os[os.name]:
+        all_os[os.name][node_name] = []
+      all_os[os.name][node_name].append(os)
 
   return all_os
 
@@ -143,7 +76,7 @@ def ListOS(opts, args):
     if len(os_node_data) != num_nodes:
       continue
 
-    if utils.all(os_node_data.values(), lambda l: _DiagnoseOSValid(l[0])):
+    if utils.all(os_node_data.values(), lambda l: l[0]):
       valid_os.append(os_name)
 
   if not opts.no_headers:
@@ -183,9 +116,8 @@ def DiagnoseOS(opts, args):
       if node_name in all_os[os_name]:
         first_os = all_os[os_name][node_name].pop(0)
         first_os_msg = ("%s (path: %s)" %
-                        (_DiagnoseOSStatus(first_os),
-                         _DiagnoseOSPath(first_os)))
-        if _DiagnoseOSValid(first_os):
+                        (first_os.status, first_os.path))
+        if first_os:
           nodes_valid[node_name] = first_os_msg
         else:
           nodes_bad[node_name] = first_os_msg
@@ -204,7 +136,7 @@ def DiagnoseOS(opts, args):
     def _OutputNodeHiddenOSStatus(dobj_list):
       for dobj in dobj_list:
         logger.ToStdout("    [hidden] path: %s, status: %s" %
-                        (_DiagnoseOSPath(dobj), _DiagnoseOSStatus(dobj)))
+                        (dobj.path, dobj.status))
 
     def _OutputPerNodeOSStatus(msg_map):
       map_k = utils.NiceSort(msg_map.keys())