diff --git a/keyserver/src/responders/keys-responders.js b/keyserver/src/responders/keys-responders.js
index 89bdeb50f..1050f4b29 100644
--- a/keyserver/src/responders/keys-responders.js
+++ b/keyserver/src/responders/keys-responders.js
@@ -1,132 +1,135 @@
 // @flow
 
 import type { Account as OlmAccount } from '@commapp/olm';
 import t, { type TUnion, type TInterface } from 'tcomb';
 
 import type {
   OlmSessionInitializationInfo,
   GetOlmSessionInitializationDataResponse,
   GetSessionPublicKeysArgs,
 } from 'lib/types/request-types.js';
 import {
   type SessionPublicKeys,
   sessionPublicKeysValidator,
 } from 'lib/types/session-types.js';
 import { ServerError } from 'lib/utils/errors.js';
 import { tShape, tNull } from 'lib/utils/validation-utils.js';
 
 import { fetchSessionPublicKeys } from '../fetchers/key-fetchers.js';
 import { verifyClientSupported } from '../session/version.js';
 import type { Viewer } from '../session/viewer.js';
 import { fetchCallUpdateOlmAccount } from '../updaters/olm-account-updater.js';
 
-type AccountKeysSet = {
+type SessionInitializationKeysSet = {
   +identityKeys: string,
   ...OlmSessionInitializationInfo,
 };
 
 export const getSessionPublicKeysInputValidator: TInterface<GetSessionPublicKeysArgs> =
   tShape<GetSessionPublicKeysArgs>({
     session: t.String,
   });
 
 type GetSessionPublicKeysResponse = SessionPublicKeys | null;
 export const getSessionPublicKeysResponseValidator: TUnion<GetSessionPublicKeysResponse> =
   t.union([sessionPublicKeysValidator, tNull]);
 
 async function getSessionPublicKeysResponder(
   viewer: Viewer,
   request: GetSessionPublicKeysArgs,
 ): Promise<GetSessionPublicKeysResponse> {
   if (!viewer.loggedIn) {
     return null;
   }
   return await fetchSessionPublicKeys(request.session);
 }
 
-async function retrieveAccountKeysSet(
+function retrieveSessionInitializationKeysSet(
   account: OlmAccount,
-): Promise<AccountKeysSet> {
+): SessionInitializationKeysSet {
   const identityKeys = account.identity_keys();
 
   const prekey = account.prekey();
   const prekeySignature = account.prekey_signature();
 
   if (!prekeySignature) {
-    throw new ServerError('prekey_validation_failure');
+    throw new ServerError('invalid_prekey');
   }
 
   account.generate_one_time_keys(1);
   const oneTimeKey = account.one_time_keys();
   account.mark_keys_as_published();
 
   return { identityKeys, oneTimeKey, prekey, prekeySignature };
 }
 
 async function getOlmSessionInitializationDataResponder(
   viewer: Viewer,
 ): Promise<GetOlmSessionInitializationDataResponse> {
   await verifyClientSupported(viewer);
 
   const {
     identityKeys: notificationsIdentityKeys,
     prekey: notificationsPrekey,
     prekeySignature: notificationsPrekeySignature,
     oneTimeKey: notificationsOneTimeKey,
-  } = await fetchCallUpdateOlmAccount('notifications', retrieveAccountKeysSet);
+  } = await fetchCallUpdateOlmAccount(
+    'notifications',
+    retrieveSessionInitializationKeysSet,
+  );
 
   const contentAccountCallback = async (account: OlmAccount) => {
     const {
       identityKeys: contentIdentityKeys,
       oneTimeKey,
       prekey,
       prekeySignature,
-    } = await retrieveAccountKeysSet(account);
+    } = await retrieveSessionInitializationKeysSet(account);
 
     const identityKeysBlob = {
       primaryIdentityPublicKeys: JSON.parse(contentIdentityKeys),
       notificationIdentityPublicKeys: JSON.parse(notificationsIdentityKeys),
     };
     const identityKeysBlobPayload = JSON.stringify(identityKeysBlob);
     const signedIdentityKeysBlob = {
       payload: identityKeysBlobPayload,
       signature: account.sign(identityKeysBlobPayload),
     };
 
     return {
       signedIdentityKeysBlob,
       oneTimeKey,
       prekey,
       prekeySignature,
     };
   };
 
   const {
     signedIdentityKeysBlob,
     prekey: contentPrekey,
     prekeySignature: contentPrekeySignature,
     oneTimeKey: contentOneTimeKey,
   } = await fetchCallUpdateOlmAccount('content', contentAccountCallback);
 
   const notifInitializationInfo = {
     prekey: notificationsPrekey,
     prekeySignature: notificationsPrekeySignature,
     oneTimeKey: notificationsOneTimeKey,
   };
   const contentInitializationInfo = {
     prekey: contentPrekey,
     prekeySignature: contentPrekeySignature,
     oneTimeKey: contentOneTimeKey,
   };
 
   return {
     signedIdentityKeysBlob,
     contentInitializationInfo,
     notifInitializationInfo,
   };
 }
 
 export {
   getSessionPublicKeysResponder,
   getOlmSessionInitializationDataResponder,
 };