diff --git a/mirror/database.py b/mirror/database.py
index 3cbcf6d..5396b4a 100644
--- a/mirror/database.py
+++ b/mirror/database.py
@@ -24,7 +24,7 @@
 
     def __eq__(self, other):
         if not isinstance(other, item):
-            return NotImplemented
+            return NotImplementedError
 
         return (self.name == other.name and self.size == other.size and
                 self.timestamp == other.timestamp)
@@ -46,7 +46,7 @@
         Should be implemented to open and read the persistent contents of
         the database and return it as a key->value dictionary.
         """
-        raise NotImplemented('get_dictionary not implemented')
+        raise NotImplementedError('get_dictionary not implemented')
 
 
     def merge_dictionary(self, values):
@@ -55,7 +55,7 @@
         database persistent contents (ie to update existent entries and to add
         those that do not exist).
         """
-        raise NotImplemented('merge_dictionary not implemented')
+        raise NotImplementedError('merge_dictionary not implemented')
 
 
 class dict_database(database):
diff --git a/mirror/source.py b/mirror/source.py
index ec60250..4c6e51c 100644
--- a/mirror/source.py
+++ b/mirror/source.py
@@ -24,7 +24,7 @@
 
 
     def get_new_files(self):
-        raise NotImplemented('get_new_files not implemented')
+        raise NotImplementedError('get_new_files not implemented')
 
 
     def store_files(self, files):
diff --git a/mirror/trigger.py b/mirror/trigger.py
index 87e5e6d..f1b5091 100644
--- a/mirror/trigger.py
+++ b/mirror/trigger.py
@@ -1,4 +1,4 @@
-import email.Message, os, re, smtplib
+import email, os, re, smtplib
 
 from autotest_lib.server import frontend
 
@@ -32,7 +32,7 @@
 
         @param kernel_list: a sequence of kernel filenames (strings)
         """
-        raise NotImplemented('__call__ not implemented')
+        raise NotImplementedError('__call__ not implemented')
 
 
 class map_action(base_action):