diff --git a/github/GithubException.py b/github/GithubException.py
index 12c9af62..53e2d302 100644
--- a/github/GithubException.py
+++ b/github/GithubException.py
@@ -5,6 +5,7 @@
 # Copyright 2012 Vincent Jacques <vincent@vincent-jacques.net>                 #
 # Copyright 2012 Zearin <zearin@gonk.net>                                      #
 # Copyright 2013 Vincent Jacques <vincent@vincent-jacques.net>                 #
+# Copyright 2013 AKFish <akfish@gmail.com>                                     #
 #                                                                              #
 # This file is part of PyGithub. http://jacquev6.github.com/PyGithub/          #
 #                                                                              #
@@ -76,3 +77,8 @@ class RateLimitExceededException(GithubException):
     """
     Exception raised when the rate limit is exceeded (when Github API replies with a 403 rate limit exceeded HTML status)
     """
+
+class NotModifiedException(GithubException):
+    """
+    Exception raised when conditional request is made to a resoure that has not changed
+    """
diff --git a/github/GithubObject.py b/github/GithubObject.py
index ae71cf7c..6c68ce1f 100644
--- a/github/GithubObject.py
+++ b/github/GithubObject.py
@@ -157,7 +157,7 @@ class GithubObject(object):
             self._storeAndUseAttributes(data)
             self.__completed = True
             return True
-        except: #GithubException.NotModifiedException:
+        except GithubException.NotModifiedException:
             return False
 
 class NonCompletableGithubObject(GithubObject):