diff --git a/luigi/contrib/target.py b/luigi/contrib/target.py
index <HASH>..<HASH> 100644
--- a/luigi/contrib/target.py
+++ b/luigi/contrib/target.py
@@ -4,7 +4,7 @@ import types
 logger = logging.getLogger('luigi-interface')
 
 
-class CascadingClient():
+class CascadingClient(object):
 
     """
     A FilesystemClient that will cascade failing function calls through a list
diff --git a/luigi/event.py b/luigi/event.py
index <HASH>..<HASH> 100644
--- a/luigi/event.py
+++ b/luigi/event.py
@@ -13,7 +13,7 @@
 # the License.
 
 
-class Event:
+class Event(object):
     # TODO nice descriptive subclasses of Event instead of strings? pass their instances to the callback instead of an undocumented arg list?
     DEPENDENCY_DISCOVERED = "event.core.dependency.discovered"  # triggered for every (task, upstream task) pair discovered in a jobflow
     DEPENDENCY_MISSING = "event.core.dependency.missing"
Do not use old-style classes.