diff --git a/CHANGES/3644.bugfix b/CHANGES/3644.bugfix
new file mode 100644
index 00000000000..d124704c50a
--- /dev/null
+++ b/CHANGES/3644.bugfix
@@ -0,0 +1 @@
+Fix _keepalive field in __slots__ of web_protocol.RequestHandler.
diff --git a/aiohttp/web_protocol.py b/aiohttp/web_protocol.py
index d44ddcdf048..0b51fba4580 100644
--- a/aiohttp/web_protocol.py
+++ b/aiohttp/web_protocol.py
@@ -106,7 +106,7 @@ class RequestHandler(BaseProtocol):
     """
     KEEPALIVE_RESCHEDULE_DELAY = 1
 
-    __slots__ = ('_request_count', '_keep_alive', '_manager',
+    __slots__ = ('_request_count', '_keepalive', '_manager',
                  '_request_handler', '_request_factory', '_tcp_keepalive',
                  '_keepalive_time', '_keepalive_handle', '_keepalive_timeout',
                  '_lingering_time', '_messages', '_message_tail',