diff --git a/econtext/core.py b/econtext/core.py
index 461ced6a..7d4fbc3b 100644
--- a/econtext/core.py
+++ b/econtext/core.py
@@ -560,31 +560,25 @@ class Broker(object):
 
     def __init__(self):
         self._alive = True
-        self._lock = threading.RLock()
         self._contexts = {}
         self._readers = set()
         self._writers = set()
         self._waker = Waker(self)
-
         self._thread = threading.Thread(target=self._broker_main,
                                         name='econtext-broker')
         self._thread.start()
 
     def _update_stream(self, stream):
         IOLOG.debug('_update_stream(%r)', stream)
-        self._lock.acquire()
-        try:
-            if stream.read_side.fd is not None:
-                self._readers.add(stream.read_side)
-            else:
-                self._readers.discard(stream.read_side)
-
-            if stream.write_side.fd is not None and stream.has_output():
-                self._writers.add(stream.write_side)
-            else:
-                self._writers.discard(stream.write_side)
-        finally:
-            self._lock.release()
+        if stream.read_side.fd is not None:
+            self._readers.add(stream.read_side)
+        else:
+            self._readers.discard(stream.read_side)
+
+        if stream.write_side.fd is not None and stream.has_output():
+            self._writers.add(stream.write_side)
+        else:
+            self._writers.discard(stream.write_side)
 
     def update_stream(self, stream):
         self._update_stream(stream)