diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 95190c1d75..f7c724c4b4 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -17,9 +17,7 @@
 import sys
 sys.dont_write_bytecode = True
 
-from synapse.storage import (
-    prepare_database, UpgradeDatabaseException,
-)
+from synapse.storage import UpgradeDatabaseException
 from synapse.storage.engines import create_engine
 
 from synapse.server import HomeServer
@@ -60,7 +58,6 @@ import os
 import re
 import resource
 import subprocess
-import sqlite3
 import yaml
 
 
@@ -322,7 +319,7 @@ def change_resource_limit(soft_file_no):
         resource.setrlimit(resource.RLIMIT_NOFILE, (soft_file_no, hard))
 
         logger.info("Set file limit to: %d", soft_file_no)
-    except (   ValueError, resource.error) as e:
+    except (ValueError, resource.error) as e:
         logger.warn("Failed to set file limit: %s", e)
 
 
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index e16414d736..231ec8169f 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -13,8 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
 from .appservice import ApplicationServiceStore
 from .directory import DirectoryStore
 from .events import EventsStore
@@ -43,8 +41,6 @@ import logging
 import os
 import re
 
-import threading
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index b62b4a3414..0f9d898e5d 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -105,7 +105,6 @@ class RegistrationStore(SQLBaseStore):
 
         defer.returnValue(user_info)
 
-
     @cached()
     # TODO(paul): Currently there's no code to invalidate this cache. That
     #   means if/when we ever add internal ways to invalidate access tokens or
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index df707f8124..8ea5756d61 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -40,7 +40,6 @@ class RoomMemberStore(SQLBaseStore):
         """
         try:
             target_user_id = event.state_key
-            domain = UserID.from_string(target_user_id).domain
         except:
             logger.exception(
                 "Failed to parse target_user_id=%s", target_user_id
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index 3e55cb81bf..4994bacd6c 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -159,4 +159,3 @@ class StateStore(SQLBaseStore):
 
 def _make_group_id(clock):
     return str(int(clock.time_msec())) + random_string(5)
-
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index 9594fe1f2b..4c3dc58662 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -375,4 +375,3 @@ class DestinationsTable(object):
         "retry_last_ts",
         "retry_interval",
     ]
-