diff --git a/sanic/server.py b/sanic/server.py
index ef9869d2..a86da9fc 100644
--- a/sanic/server.py
+++ b/sanic/server.py
@@ -60,14 +60,14 @@ class HttpProtocol(asyncio.Protocol):
     # -------------------------------------------- #
 
     def connection_made(self, transport):
-        self.connections[self] = True
+        self.connections.add(self)
         self._timeout_handler = self.loop.call_later(
             self.request_timeout, self.connection_timeout)
         self.transport = transport
         self._last_request_time = current_time
 
     def connection_lost(self, exc):
-        del self.connections[self]
+        self.connections.discard(self)
         self._timeout_handler.cancel()
         self.cleanup()
 
@@ -250,7 +250,7 @@ def serve(host, port, request_handler, error_handler, before_start=None,
 
     trigger_events(before_start, loop)
 
-    connections = {}
+    connections = set()
     signal = Signal()
     server = partial(
         HttpProtocol,
@@ -301,7 +301,7 @@ def serve(host, port, request_handler, error_handler, before_start=None,
 
         # Complete all tasks on the loop
         signal.stopped = True
-        for connection in connections.keys():
+        for connection in connections:
             connection.close_if_idle()
 
         while connections: