diff --git a/synapse/appservice/scheduler.py b/synapse/appservice/scheduler.py
index 50ad3b8e83..514148c947 100644
--- a/synapse/appservice/scheduler.py
+++ b/synapse/appservice/scheduler.py
@@ -224,5 +224,5 @@ class _Recoverer(object):
 
     @defer.inlineCallbacks
     def _get_oldest_txn(self):
-        txn = yield self.store.get_oldest_txn(self.service)
+        txn = yield self.store.get_oldest_unsent_txn(self.service)
         defer.returnValue(txn)
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 6fde7dcc66..4447c8a2e1 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -383,7 +383,7 @@ class ApplicationServiceTransactionStore(SQLBaseStore):
             service(ApplicationService): The service who the transaction is for.
             events(list<Event>): A list of events to put in the transaction.
         Returns:
-            ApplicationServiceTransaction: A new transaction.
+            AppServiceTransaction: A new transaction.
         """
         pass
 
@@ -399,3 +399,15 @@ class ApplicationServiceTransactionStore(SQLBaseStore):
             successfully.
         """
         pass
+
+    def get_oldest_unsent_txn(self, service):
+        """Get the oldest transaction which has not been sent for this
+        service.
+
+        Args:
+            service(ApplicationService): The app service to get the oldest txn.
+        Returns:
+            A Deferred which resolves to an AppServiceTransaction or
+            None.
+        """
+        pass
diff --git a/tests/appservice/test_scheduler.py b/tests/appservice/test_scheduler.py
index a31755da67..f75a6f5d95 100644
--- a/tests/appservice/test_scheduler.py
+++ b/tests/appservice/test_scheduler.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 from synapse.appservice import ApplicationServiceState, AppServiceTransaction
 from synapse.appservice.scheduler import (
-    AppServiceScheduler, _EventGrouper, _TransactionController, _Recoverer
+    _EventGrouper, _TransactionController, _Recoverer
 )
 from twisted.internet import defer
 from ..utils import MockClock