diff --git a/src/wormhole/util/observer.py b/src/wormhole/util/observer.py
deleted file mode 100644
index 25ce716..0000000
--- a/src/wormhole/util/observer.py
+++ /dev/null
@@ -1,50 +0,0 @@
-# -*- test-case-name: foolscap.test_observer -*-
-
-# many thanks to AllMyData for contributing the initial version of this code
-
-from twisted.internet import defer
-from foolscap import eventual
-
-class OneShotObserverList(object):
-    """A one-shot event distributor.
-
-    Subscribers can get a Deferred that will fire with the results of the
-    event once it finally occurs. The caller does not need to know whether
-    the event has happened yet or not: they get a Deferred in either case.
-
-    The Deferreds returned to subscribers are guaranteed to not fire in the
-    current reactor turn; instead, eventually() is used to fire them in a
-    later turn. Look at Mark Miller's 'Concurrency Among Strangers' paper on
-    erights.org for a description of why this property is useful.
-
-    I can only be fired once."""
-
-    def __init__(self):
-        self._fired = False
-        self._result = None
-        self._watchers = []
-        self.__repr__ = self._unfired_repr
-
-    def _unfired_repr(self):
-        return "<OneShotObserverList [%s]>" % (self._watchers, )
-
-    def _fired_repr(self):
-        return "<OneShotObserverList -> %s>" % (self._result, )
-
-    def whenFired(self):
-        if self._fired:
-            return eventual.fireEventually(self._result)
-        d = defer.Deferred()
-        self._watchers.append(d)
-        return d
-
-    def fire(self, result):
-        assert not self._fired
-        self._fired = True
-        self._result = result
-
-        for w in self._watchers:
-            eventual.eventually(w.callback, result)
-        del self._watchers
-        self.__repr__ = self._fired_repr
-