diff --git a/telnetlib3/server.py b/telnetlib3/server.py
index a9b808e..0921c2d 100755
--- a/telnetlib3/server.py
+++ b/telnetlib3/server.py
@@ -111,7 +111,7 @@ def check_negotiation(self, final=False):
         encoding = self.encoding(outgoing=True, incoming=True)
         if not self.waiter_encoding.done() and result:
             self.log.debug('encoding complete: {0!r}'.format(encoding))
-            self.waiter_encoding.set_result(self)
+            self.waiter_encoding.set_result(True)
 
         elif (not self.waiter_encoding.done() and
               self.writer.remote_option.get(TTYPE) is False):
@@ -120,13 +120,13 @@ def check_negotiation(self, final=False):
             # the distant end would not support it, declaring encoding failed.
             self.log.debug('encoding failed after {0:1.2f}s: {1}'
                            .format(self.duration, encoding))
-            self.waiter_encoding.set_result(self)
+            self.waiter_encoding.set_result(True)
             return parent
 
         elif not self.waiter_encoding.done() and final:
             self.log.debug('encoding failed after {0:1.2f}s: {1}'
                            .format(self.duration, encoding))
-            self.waiter_encoding.set_result(self)
+            self.waiter_encoding.set_result(True)
             return parent
 
         return parent and result
diff --git a/telnetlib3/server_base.py b/telnetlib3/server_base.py
index b7e482b..298222b 100644
--- a/telnetlib3/server_base.py
+++ b/telnetlib3/server_base.py
@@ -85,7 +85,11 @@ def connection_lost(self, exc):
         self._transport.close()
         self._waiter_connected.cancel()
         if self.shell is None:
-            self._waiter_closed.set_result(self)
+            self._waiter_closed.set_result(True)
+
+        # break circular refrences.
+        self._transport = None
+        self.reader.fn_encoding = None
 
     def connection_made(self, transport):
         """
@@ -134,7 +138,7 @@ def begin_shell(self, result):
             if asyncio.iscoroutine(coro):
                 fut = self._loop.create_task(coro)
                 fut.add_done_callback(
-                    lambda fut_obj: self._waiter_closed.set_result(self))
+                    lambda fut_obj: self._waiter_closed.set_result(True))
 
     def data_received(self, data):
         """Process bytes received by transport."""
@@ -277,11 +281,11 @@ def _check_negotiation_timer(self):
         if self.check_negotiation(final=final):
             self.log.debug('negotiation complete after {:1.2f}s.'
                            .format(self.duration))
-            self._waiter_connected.set_result(self)
+            self._waiter_connected.set_result(True)
         elif final:
             self.log.debug('negotiation failed after {:1.2f}s.'
                            .format(self.duration))
-            self._waiter_connected.set_result(self)
+            self._waiter_connected.set_result(True)
         else:
             # keep re-queuing until complete
             self._check_later = self._loop.call_later(
diff --git a/telnetlib3/stream_writer.py b/telnetlib3/stream_writer.py
index 798a808..30eaefb 100644
--- a/telnetlib3/stream_writer.py
+++ b/telnetlib3/stream_writer.py
@@ -182,6 +182,17 @@ def __init__(self, transport, protocol, *, client=False, server=False,
 
     # Base protocol methods
 
+    def close(self):
+        super().close()
+        # break circular refs
+        self._ext_callback.clear()
+        self._ext_send_callback.clear()
+        self._slc_callback.clear()
+        self._iac_callback.clear()
+        self.fn_encoding = None
+        self._protocol = None
+        self._transport = None
+
     def __repr__(self):
         """Description of stream encoding state."""
         info = ['TelnetWriter']