diff --git a/gunicorn/arbiter.py b/gunicorn/arbiter.py
index 341844811..815ac5d3d 100644
--- a/gunicorn/arbiter.py
+++ b/gunicorn/arbiter.py
@@ -584,11 +584,11 @@ def manage_workers(self):
                                   "value": active_worker_count,
                                   "mtype": "gauge"})
 
-        backlog = sum([
-            sock.get_backlog()
+        backlog = sum(
+            sock.get_backlog() or 0
             for sock in self.LISTENERS
-                if sock.get_backlog() is not None
-        ])
+        )
+
         if backlog:
             self.log.debug("socket backlog: {0}".format(backlog),
                            extra={"metric": "gunicorn.backlog",
diff --git a/gunicorn/sock.py b/gunicorn/sock.py
index 747199d1c..f88bac626 100644
--- a/gunicorn/sock.py
+++ b/gunicorn/sock.py
@@ -97,7 +97,7 @@ def set_options(self, sock, bound=False):
     def get_backlog(self):
         if self.sock and PLATFORM == "linux":
             # tcp_info struct from include/uapi/linux/tcp.h
-            fmt = 'B'*8+'I'*24
+            fmt = 'B' * 8 + 'I' * 24
             try:
                 tcp_info_struct = self.sock.getsockopt(socket.IPPROTO_TCP,
                                                        socket.TCP_INFO, 104)