diff --git a/github/GithubObjects/GithubObject/GithubObject.py b/github/GithubObjects/GithubObject/GithubObject.py
index 30d515e9..f8b56fb8 100644
--- a/github/GithubObjects/GithubObject/GithubObject.py
+++ b/github/GithubObjects/GithubObject/GithubObject.py
@@ -84,8 +84,11 @@ def GithubObject( className, *attributePolicies ):
 
         def _updateAttributes( self, attributes ):
             for attributeName, attributeValue in attributes.iteritems():
-                attributeDefinition = GithubObject.__attributeDefinitions[ attributeName ]
-                self.__attributes[ attributeName ] = attributeDefinition.getValueFromRawValue( self, attributeValue )
+                try:
+                    attributeDefinition = GithubObject.__attributeDefinitions[ attributeName ]
+                    self.__attributes[ attributeName ] = attributeDefinition.getValueFromRawValue( self, attributeValue )
+                except KeyError:
+                    pass
 
         def _markAsCompleted( self ):
             for attributeName, attributeDefinition in GithubObject.__attributeDefinitions.iteritems():