diff --git a/synapse/metrics/background_process_metrics.py b/synapse/metrics/background_process_metrics.py
index 264fb93892..167167be0a 100644
--- a/synapse/metrics/background_process_metrics.py
+++ b/synapse/metrics/background_process_metrics.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import six
 import threading
 
+import six
+
 from prometheus_client.core import REGISTRY, Counter, GaugeMetricFamily
 
 from twisted.internet import defer