diff --git a/lib/utils/validation-utils.js b/lib/utils/validation-utils.js
index a7532f7fb..7b81a68e8 100644
--- a/lib/utils/validation-utils.js
+++ b/lib/utils/validation-utils.js
@@ -1,145 +1,150 @@
 // @flow
 
 import invariant from 'invariant';
 import t from 'tcomb';
 import type {
   TStructProps,
   TIrreducible,
   TRefinement,
   TEnums,
   TInterface,
   TUnion,
   TType,
 } from 'tcomb';
 
 import {
   validEmailRegex,
   oldValidUsernameRegex,
   validHexColorRegex,
 } from '../shared/account-utils.js';
 import type { PlatformDetails } from '../types/device-types';
 import type {
   MediaMessageServerDBContent,
   PhotoMessageServerDBContent,
   VideoMessageServerDBContent,
 } from '../types/messages/media';
 
 function tBool(value: boolean): TIrreducible<boolean> {
   return t.irreducible(value.toString(), x => x === value);
 }
 
 function tString(value: string): TIrreducible<string> {
   return t.irreducible(`'${value}'`, x => x === value);
 }
 
 function tNumber(value: number): TIrreducible<number> {
   return t.irreducible(value.toString(), x => x === value);
 }
 
 function tShape<T>(spec: TStructProps<T>): TInterface<T> {
   return t.interface(spec, { strict: true });
 }
 
 export type TRegex = TRefinement<string>;
 function tRegex(regex: RegExp): TRegex {
   return t.refinement(t.String, val => regex.test(val));
 }
 
 function tNumEnum(nums: $ReadOnlyArray<number>): TRefinement<number> {
   return t.refinement(t.Number, (input: number) => {
     for (const num of nums) {
       if (input === num) {
         return true;
       }
     }
     return false;
   });
 }
 const tNull: TIrreducible<null> = t.irreducible('null', x => x === null);
 const tDate: TRegex = tRegex(/^[0-9]{4}-[0-1][0-9]-[0-3][0-9]$/);
 const tColor: TRegex = tRegex(validHexColorRegex); // we don't include # char
 const tPlatform: TEnums = t.enums.of([
   'ios',
   'android',
   'web',
   'windows',
   'macos',
 ]);
 const tDeviceType: TEnums = t.enums.of(['ios', 'android']);
 const tPlatformDetails: TInterface<PlatformDetails> = tShape({
   platform: tPlatform,
   codeVersion: t.maybe(t.Number),
   stateVersion: t.maybe(t.Number),
   majorDesktopVersion: t.maybe(t.Number),
 });
 const tPassword: TRefinement<string> = t.refinement(
   t.String,
   (password: string) => !!password,
 );
 const tCookie: TRegex = tRegex(/^(user|anonymous)=[0-9]+:[0-9a-f]+$/);
 const tEmail: TRegex = tRegex(validEmailRegex);
 const tOldValidUsername: TRegex = tRegex(oldValidUsernameRegex);
 const tID: TRefinement<string> = t.refinement(t.String, (id: string) => !!id);
+const tUserID: TRefinement<string> = t.refinement(
+  t.String,
+  (id: string) => !!id,
+);
 
 const tMediaMessagePhoto: TInterface<PhotoMessageServerDBContent> = tShape({
   type: tString('photo'),
   uploadID: tID,
 });
 
 const tMediaMessageVideo: TInterface<VideoMessageServerDBContent> = tShape({
   type: tString('video'),
   uploadID: tID,
   thumbnailUploadID: tID,
 });
 
 const tMediaMessageMedia: TUnion<MediaMessageServerDBContent> = t.union([
   tMediaMessagePhoto,
   tMediaMessageVideo,
 ]);
 
 function assertWithValidator<T>(data: mixed, validator: TType<T>): T {
   invariant(validator.is(data), "data isn't of type T");
   return (data: any);
 }
 
 const ashoatKeyserverID = '256';
 
 const idSchemaRegex = '(?:[0-9]+\\|)?[0-9]+';
 
 const pendingThreadIDRegex = `pending/(type[0-9]+/[0-9]+(\\+[0-9]+)*|sidebar/${idSchemaRegex})`;
 
 const chatNameMaxLength = 191;
 const chatNameMinLength = 0;
 const secondCharRange = `{${chatNameMinLength},${chatNameMaxLength}}`;
 const validChatNameRegexString = `.${secondCharRange}`;
 const validChatNameRegex: RegExp = new RegExp(`^${validChatNameRegexString}$`);
 
 export {
   tBool,
   tString,
   tNumber,
   tShape,
   tRegex,
   tNumEnum,
   tNull,
   tDate,
   tColor,
   tPlatform,
   tDeviceType,
   tPlatformDetails,
   tPassword,
   tCookie,
   tEmail,
   tOldValidUsername,
   tID,
+  tUserID,
   tMediaMessagePhoto,
   tMediaMessageVideo,
   tMediaMessageMedia,
   assertWithValidator,
   ashoatKeyserverID,
   idSchemaRegex,
   pendingThreadIDRegex,
   validChatNameRegex,
   validChatNameRegexString,
   chatNameMaxLength,
 };