diff --git a/keyserver/src/shared/state-sync/current-user-state-sync-spec.js b/keyserver/src/shared/state-sync/current-user-state-sync-spec.js
index d9da2413c..c1f5f2303 100644
--- a/keyserver/src/shared/state-sync/current-user-state-sync-spec.js
+++ b/keyserver/src/shared/state-sync/current-user-state-sync-spec.js
@@ -1,21 +1,22 @@
 // @flow
 
 import { currentUserStateSyncSpec as libSpec } from 'lib/shared/state-sync/current-user-state-sync-spec.js';
 import type { CurrentUserInfo } from 'lib/types/user-types.js';
 
 import type { ServerStateSyncSpec } from './state-sync-spec.js';
 import { fetchCurrentUserInfo } from '../../fetchers/user-fetchers.js';
 import type { Viewer } from '../../session/viewer.js';
 
 export const currentUserStateSyncSpec: ServerStateSyncSpec<
   CurrentUserInfo,
   CurrentUserInfo,
+  CurrentUserInfo,
 > = Object.freeze({
   fetch(viewer: Viewer) {
     return fetchCurrentUserInfo(viewer);
   },
   fetchFullSocketSyncPayload(viewer: Viewer) {
     return fetchCurrentUserInfo(viewer);
   },
   ...libSpec,
 });
diff --git a/keyserver/src/shared/state-sync/entries-state-sync-spec.js b/keyserver/src/shared/state-sync/entries-state-sync-spec.js
index b215ef5ba..110ee928b 100644
--- a/keyserver/src/shared/state-sync/entries-state-sync-spec.js
+++ b/keyserver/src/shared/state-sync/entries-state-sync-spec.js
@@ -1,38 +1,39 @@
 // @flow
 
 import { serverEntryInfosObject } from 'lib/shared/entry-utils.js';
 import { entriesStateSyncSpec as libSpec } from 'lib/shared/state-sync/entries-state-sync-spec.js';
 import type {
   CalendarQuery,
   RawEntryInfo,
   RawEntryInfos,
 } from 'lib/types/entry-types.js';
 
 import type { ServerStateSyncSpec } from './state-sync-spec.js';
 import {
   fetchEntryInfos,
   fetchEntryInfosByID,
 } from '../../fetchers/entry-fetchers.js';
 import type { Viewer } from '../../session/viewer.js';
 
 export const entriesStateSyncSpec: ServerStateSyncSpec<
   RawEntryInfos,
   $ReadOnlyArray<RawEntryInfo>,
+  RawEntryInfo,
 > = Object.freeze({
   async fetch(viewer: Viewer, ids?: $ReadOnlySet<string>) {
     if (ids) {
       return fetchEntryInfosByID(viewer, ids);
     }
     const query = [viewer.calendarQuery];
     const entriesResult = await fetchEntryInfos(viewer, query);
     return serverEntryInfosObject(entriesResult.rawEntryInfos);
   },
   async fetchFullSocketSyncPayload(
     viewer: Viewer,
     query: $ReadOnlyArray<CalendarQuery>,
   ) {
     const result = await fetchEntryInfos(viewer, query);
     return result.rawEntryInfos;
   },
   ...libSpec,
 });
diff --git a/keyserver/src/shared/state-sync/state-sync-spec.js b/keyserver/src/shared/state-sync/state-sync-spec.js
index 6899cbd6a..7a158a15c 100644
--- a/keyserver/src/shared/state-sync/state-sync-spec.js
+++ b/keyserver/src/shared/state-sync/state-sync-spec.js
@@ -1,15 +1,15 @@
 // @flow
 
 import type { StateSyncSpec } from 'lib/shared/state-sync/state-sync-spec.js';
 import type { CalendarQuery } from 'lib/types/entry-types.js';
 
 import type { Viewer } from '../../session/viewer.js';
 
-export type ServerStateSyncSpec<Infos, FullSocketSyncPayload, Info = empty> = {
+export type ServerStateSyncSpec<Infos, FullSocketSyncPayload, Info> = {
   +fetch: (viewer: Viewer, ids?: $ReadOnlySet<string>) => Promise<Infos>,
   +fetchFullSocketSyncPayload: (
     viewer: Viewer,
     calendarQuery: $ReadOnlyArray<CalendarQuery>,
   ) => Promise<FullSocketSyncPayload>,
   ...StateSyncSpec<Infos, Info>,
 };
diff --git a/keyserver/src/shared/state-sync/threads-state-sync-spec.js b/keyserver/src/shared/state-sync/threads-state-sync-spec.js
index fe968d246..5812de123 100644
--- a/keyserver/src/shared/state-sync/threads-state-sync-spec.js
+++ b/keyserver/src/shared/state-sync/threads-state-sync-spec.js
@@ -1,24 +1,28 @@
 // @flow
 
 import { threadsStateSyncSpec as libSpec } from 'lib/shared/state-sync/threads-state-sync-spec.js';
-import type { RawThreadInfos } from 'lib/types/thread-types.js';
+import {
+  type RawThreadInfos,
+  type RawThreadInfo,
+} from 'lib/types/thread-types.js';
 
 import type { ServerStateSyncSpec } from './state-sync-spec.js';
 import { fetchThreadInfos } from '../../fetchers/thread-fetchers.js';
 import type { Viewer } from '../../session/viewer.js';
 
 export const threadsStateSyncSpec: ServerStateSyncSpec<
   RawThreadInfos,
   RawThreadInfos,
+  RawThreadInfo,
 > = Object.freeze({
   async fetch(viewer: Viewer, ids?: $ReadOnlySet<string>) {
     const filter = ids ? { threadIDs: ids } : undefined;
     const result = await fetchThreadInfos(viewer, filter);
     return result.threadInfos;
   },
   async fetchFullSocketSyncPayload(viewer: Viewer) {
     const result = await fetchThreadInfos(viewer);
     return result.threadInfos;
   },
   ...libSpec,
 });
diff --git a/lib/shared/state-sync/current-user-state-sync-spec.js b/lib/shared/state-sync/current-user-state-sync-spec.js
index 7399cd328..81414a150 100644
--- a/lib/shared/state-sync/current-user-state-sync-spec.js
+++ b/lib/shared/state-sync/current-user-state-sync-spec.js
@@ -1,21 +1,23 @@
 // @flow
 
 import type { StateSyncSpec } from './state-sync-spec.js';
 import {
   type CurrentUserInfo,
   currentUserInfoValidator,
 } from '../../types/user-types.js';
 import { convertClientIDsToServerIDs } from '../../utils/conversion-utils.js';
 import { ashoatKeyserverID } from '../../utils/validation-utils.js';
 
-export const currentUserStateSyncSpec: StateSyncSpec<CurrentUserInfo> =
-  Object.freeze({
-    hashKey: 'currentUserInfo',
-    convertClientToServerInfos(info: CurrentUserInfo) {
-      return convertClientIDsToServerIDs(
-        ashoatKeyserverID,
-        currentUserInfoValidator,
-        info,
-      );
-    },
-  });
+export const currentUserStateSyncSpec: StateSyncSpec<
+  CurrentUserInfo,
+  CurrentUserInfo,
+> = Object.freeze({
+  hashKey: 'currentUserInfo',
+  convertClientToServerInfos(info: CurrentUserInfo) {
+    return convertClientIDsToServerIDs(
+      ashoatKeyserverID,
+      currentUserInfoValidator,
+      info,
+    );
+  },
+});
diff --git a/lib/shared/state-sync/entries-state-sync-spec.js b/lib/shared/state-sync/entries-state-sync-spec.js
index 4023e242c..cc98e0f2d 100644
--- a/lib/shared/state-sync/entries-state-sync-spec.js
+++ b/lib/shared/state-sync/entries-state-sync-spec.js
@@ -1,43 +1,43 @@
 // @flow
 
 import t from 'tcomb';
 
 import type { StateSyncSpec } from './state-sync-spec.js';
 import {
   type CalendarQuery,
   type RawEntryInfos,
   rawEntryInfoValidator,
+  type RawEntryInfo,
 } from '../../types/entry-types.js';
 import { convertClientIDsToServerIDs } from '../../utils/conversion-utils.js';
 import { values } from '../../utils/objects.js';
 import { ashoatKeyserverID, tID } from '../../utils/validation-utils.js';
 import {
   filterRawEntryInfosByCalendarQuery,
   serverEntryInfosObject,
 } from '../entry-utils.js';
 
-export const entriesStateSyncSpec: StateSyncSpec<RawEntryInfos> = Object.freeze(
-  {
+export const entriesStateSyncSpec: StateSyncSpec<RawEntryInfos, RawEntryInfo> =
+  Object.freeze({
     hashKey: 'entryInfos',
     innerHashSpec: {
       hashKey: 'entryInfo',
       deleteKey: 'deleteEntryIDs',
       rawInfosKey: 'rawEntryInfos',
     },
     convertClientToServerInfos(
       infos: RawEntryInfos,
       calendarQuery: CalendarQuery,
     ) {
       const filteredEntryInfos = filterRawEntryInfosByCalendarQuery(
         serverEntryInfosObject(values(infos)),
         calendarQuery,
       );
 
       return convertClientIDsToServerIDs(
         ashoatKeyserverID,
         t.dict(tID, rawEntryInfoValidator),
         filteredEntryInfos,
       );
     },
-  },
-);
+  });
diff --git a/lib/shared/state-sync/state-sync-spec.js b/lib/shared/state-sync/state-sync-spec.js
index a40eaa6f1..f8f7cd218 100644
--- a/lib/shared/state-sync/state-sync-spec.js
+++ b/lib/shared/state-sync/state-sync-spec.js
@@ -1,17 +1,17 @@
 // @flow
 
 import type { CalendarQuery } from '../../types/entry-types.js';
 
-export type StateSyncSpec<Infos, Info = empty> = {
+export type StateSyncSpec<Infos, Info> = {
   +hashKey: string,
   +innerHashSpec?: {
     +hashKey: string,
     +deleteKey: string,
     +rawInfosKey: string,
     +additionalDeleteCondition?: Info => boolean,
   },
   +convertClientToServerInfos: (
     infos: Infos,
     calendarQuery: CalendarQuery,
   ) => Infos,
 };
diff --git a/lib/shared/state-sync/state-sync-specs.js b/lib/shared/state-sync/state-sync-specs.js
index 99256699e..6a2edcb42 100644
--- a/lib/shared/state-sync/state-sync-specs.js
+++ b/lib/shared/state-sync/state-sync-specs.js
@@ -1,18 +1,18 @@
 // @flow
 
 import { currentUserStateSyncSpec } from './current-user-state-sync-spec.js';
 import { entriesStateSyncSpec } from './entries-state-sync-spec.js';
 import type { StateSyncSpec } from './state-sync-spec.js';
 import { threadsStateSyncSpec } from './threads-state-sync-spec.js';
 import { usersStateSyncSpec } from './users-state-sync-spec.js';
 
 export const stateSyncSpecs = Object.freeze({
   threads: threadsStateSyncSpec,
   entries: entriesStateSyncSpec,
   currentUser: currentUserStateSyncSpec,
   users: usersStateSyncSpec,
 });
 
 (stateSyncSpecs: {
-  +[string]: StateSyncSpec<any>,
+  +[string]: StateSyncSpec<any, any>,
 });
diff --git a/lib/shared/state-sync/threads-state-sync-spec.js b/lib/shared/state-sync/threads-state-sync-spec.js
index aace2dbc1..9e611b773 100644
--- a/lib/shared/state-sync/threads-state-sync-spec.js
+++ b/lib/shared/state-sync/threads-state-sync-spec.js
@@ -1,28 +1,31 @@
 // @flow
 
 import t from 'tcomb';
 
 import type { StateSyncSpec } from './state-sync-spec.js';
 import {
   type RawThreadInfos,
+  type RawThreadInfo,
   rawThreadInfoValidator,
 } from '../../types/thread-types.js';
 import { convertClientIDsToServerIDs } from '../../utils/conversion-utils.js';
 import { ashoatKeyserverID, tID } from '../../utils/validation-utils.js';
 
-export const threadsStateSyncSpec: StateSyncSpec<RawThreadInfos> =
-  Object.freeze({
-    hashKey: 'threadInfos',
-    innerHashSpec: {
-      hashKey: 'threadInfo',
-      deleteKey: 'deleteThreadIDs',
-      rawInfosKey: 'rawThreadInfos',
-    },
-    convertClientToServerInfos(infos: RawThreadInfos) {
-      return convertClientIDsToServerIDs(
-        ashoatKeyserverID,
-        t.dict(tID, rawThreadInfoValidator),
-        infos,
-      );
-    },
-  });
+export const threadsStateSyncSpec: StateSyncSpec<
+  RawThreadInfos,
+  RawThreadInfo,
+> = Object.freeze({
+  hashKey: 'threadInfos',
+  innerHashSpec: {
+    hashKey: 'threadInfo',
+    deleteKey: 'deleteThreadIDs',
+    rawInfosKey: 'rawThreadInfos',
+  },
+  convertClientToServerInfos(infos: RawThreadInfos) {
+    return convertClientIDsToServerIDs(
+      ashoatKeyserverID,
+      t.dict(tID, rawThreadInfoValidator),
+      infos,
+    );
+  },
+});