diff --git a/spec/unit/crypto/algorithms/megolm.spec.js b/spec/unit/crypto/algorithms/megolm.spec.js
index a3134d477..e1da35db5 100644
--- a/spec/unit/crypto/algorithms/megolm.spec.js
+++ b/spec/unit/crypto/algorithms/megolm.spec.js
@@ -11,7 +11,6 @@ import logger from '../../../../lib/logger';
 import TestClient from '../../../TestClient';
 import olmlib from '../../../../lib/crypto/olmlib';
 import Room from '../../../../lib/models/room';
-import DeviceInfo from '../../../../lib/crypto/deviceinfo';
 
 const MatrixEvent = sdk.MatrixEvent;
 const MegolmDecryption = algorithms.DECRYPTION_CLASSES['m.megolm.v1.aes-sha2'];
diff --git a/src/crypto/algorithms/megolm.js b/src/crypto/algorithms/megolm.js
index ecdeed6c0..82d54dfc6 100644
--- a/src/crypto/algorithms/megolm.js
+++ b/src/crypto/algorithms/megolm.js
@@ -356,6 +356,10 @@ MegolmEncryption.prototype._prepareNewSession = async function() {
  * @param {object<string, module:crypto/deviceinfo[]>} devicesByUser
  *    map from userid to list of devices
  *
+ * @param {array<object>} errorDevices
+ *    array that will be populated with the devices that can't get an
+ *    olm session for
+ *
  * @return {array<object<userid, deviceInfo>>}
  */
 MegolmEncryption.prototype._splitUserDeviceMap = function(
@@ -665,6 +669,10 @@ MegolmEncryption.prototype.reshareKeyWithDevice = async function(
  *
  * @param {object<string, module:crypto/deviceinfo[]>} devicesByUser
  *    map from userid to list of devices
+ *
+ * @param {array<object>} errorDevices
+ *    array that will be populated with the devices that we can't get an
+ *    olm session for
  */
 MegolmEncryption.prototype._shareKeyWithDevices = async function(
     session, devicesByUser, errorDevices,
diff --git a/src/crypto/store/indexeddb-crypto-store-backend.js b/src/crypto/store/indexeddb-crypto-store-backend.js
index 7b78f2e09..5b81f581e 100644
--- a/src/crypto/store/indexeddb-crypto-store-backend.js
+++ b/src/crypto/store/indexeddb-crypto-store-backend.js
@@ -467,6 +467,7 @@ export class Backend {
         return result;
     }
 
+    // FIXME: we should probably prune this when devices get deleted
     async filterOutNotifiedErrorDevices(devices) {
         const txn = this._db.transaction("notified_error_devices", "readwrite");
         const objectStore = txn.objectStore("notified_error_devices");