diff --git a/synapse/config/repository.py b/synapse/config/repository.py
index 407c8d6c24..b71d30227c 100644
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -14,7 +14,6 @@
 # limitations under the License.
 
 from ._base import Config
-import os
 
 class ContentRepositoryConfig(Config):
     def __init__(self, args):
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index 1ebbeab2e7..32d9c1392b 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -105,7 +105,7 @@ class DataStore(RoomMemberStore, RoomStore,
                 stream_ordering=stream_ordering,
                 is_new_state=is_new_state,
             )
-        except _RollbackButIsFineException as e:
+        except _RollbackButIsFineException:
             pass
 
     @defer.inlineCallbacks
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 958e730591..ceeef5880e 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -18,7 +18,6 @@ from twisted.internet import defer
 from ._base import SQLBaseStore
 
 from synapse.api.constants import Membership
-from synapse.util.logutils import log_function
 
 import logging