diff --git a/federationapi/queue/queue_test.go b/federationapi/queue/queue_test.go
index 6da9e6b30..40419b91f 100644
--- a/federationapi/queue/queue_test.go
+++ b/federationapi/queue/queue_test.go
@@ -1004,9 +1004,12 @@ func TestQueueInteractsWithRealDatabasePDUAndEDU(t *testing.T) {
 		err := queues.SendEvent(ev, "localhost", []gomatrixserverlib.ServerName{destination})
 		assert.NoError(t, err)
 
+		// NOTE : The server can be blacklisted before this, so manually inject the event
+		// into the database.
 		edu := mustCreateEDU(t)
-		errEDU := queues.SendEDU(edu, "localhost", []gomatrixserverlib.ServerName{destination})
-		assert.NoError(t, errEDU)
+		ephemeralJSON, _ := json.Marshal(edu)
+		nid, _ := db.StoreJSON(pc.Context(), string(ephemeralJSON))
+		db.AssociateEDUWithDestination(pc.Context(), destination, nid, edu.Type, nil)
 
 		checkBlacklisted := func(log poll.LogT) poll.Result {
 			if fc.txCount.Load() == failuresUntilBlacklist {
diff --git a/keyserver/internal/internal.go b/keyserver/internal/internal.go
index 89621aa87..49ef03054 100644
--- a/keyserver/internal/internal.go
+++ b/keyserver/internal/internal.go
@@ -472,7 +472,9 @@ func (a *KeyInternalAPI) queryRemoteKeys(
 		close(resultCh)
 	}()
 
-	for result := range resultCh {
+	processResult := func(result *gomatrixserverlib.RespQueryKeys) {
+		respMu.Lock()
+		defer respMu.Unlock()
 		for userID, nest := range result.DeviceKeys {
 			res.DeviceKeys[userID] = make(map[string]json.RawMessage)
 			for deviceID, deviceKey := range nest {
@@ -495,6 +497,10 @@ func (a *KeyInternalAPI) queryRemoteKeys(
 		// TODO: do we want to persist these somewhere now
 		// that we have fetched them?
 	}
+
+	for result := range resultCh {
+		processResult(result)
+	}
 }
 
 func (a *KeyInternalAPI) queryRemoteKeysOnServer(