diff --git a/synapse/notifier.py b/synapse/notifier.py
index 2d683718f..2e7525b7d 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -26,7 +26,6 @@ from synapse.handlers.presence import format_user_presence_state
 from synapse.metrics import LaterGauge
 from synapse.types import StreamToken
 from synapse.util.async_helpers import (
-    DeferredTimeoutError,
     ObservableDeferred,
     timeout_deferred,
 )
@@ -354,7 +353,7 @@ class Notifier(object):
                     # Update the prev_token to the current_token since nothing
                     # has happened between the old prev_token and the current_token
                     prev_token = current_token
-                except DeferredTimeoutError:
+                except defer.TimeoutError:
                     break
                 except defer.CancelledError:
                     break
@@ -568,7 +567,7 @@ class Notifier(object):
             try:
                 with PreserveLoggingContext():
                     yield listener.deferred
-            except DeferredTimeoutError:
+            except defer.TimeoutError:
                 break
             except defer.CancelledError:
                 break
diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py
index 2b2e85ecb..ec7b2c967 100644
--- a/synapse/util/async_helpers.py
+++ b/synapse/util/async_helpers.py
@@ -374,16 +374,10 @@ class ReadWriteLock(object):
         defer.returnValue(_ctx_manager())
 
 
-class DeferredTimeoutError(Exception):
-    """
-    This error is raised by default when a L{Deferred} times out.
-    """
-
-
 def _cancelled_to_timed_out_error(value, timeout):
     if isinstance(value, failure.Failure):
         value.trap(CancelledError)
-        raise DeferredTimeoutError(timeout, "Deferred")
+        raise defer.TimeoutError(timeout, "Deferred")
     return value
 
 
@@ -408,7 +402,7 @@ def timeout_deferred(deferred, timeout, reactor, on_timeout_cancel=None):
             the timeout.
 
             The default callable (if none is provided) will translate a
-            CancelledError Failure into a DeferredTimeoutError.
+            CancelledError Failure into a defer.TimeoutError.
 
     Returns:
         Deferred
@@ -427,7 +421,7 @@ def timeout_deferred(deferred, timeout, reactor, on_timeout_cancel=None):
             logger.exception("Canceller failed during timeout")
 
         if not new_d.called:
-            new_d.errback(DeferredTimeoutError(timeout, "Deferred"))
+            new_d.errback(defer.TimeoutError(timeout, "Deferred"))
 
     delayed_call = reactor.callLater(timeout, time_it_out)