diff --git a/lib/hooks/ens-cache.js b/lib/hooks/ens-cache.js
--- a/lib/hooks/ens-cache.js
+++ b/lib/hooks/ens-cache.js
@@ -5,11 +5,9 @@
 import { ENSCacheContext } from '../components/ens-cache-provider.react';
 import { userIdentifiedByETHAddress } from '../shared/account-utils';
 import { stringForUser } from '../shared/user-utils';
-import type { RelativeMemberInfo } from '../types/thread-types';
-import type { RelativeUserInfo } from '../types/user-types';
 
 function useStringForUser(
-  user: ?(RelativeUserInfo | RelativeMemberInfo),
+  user: ?{ +username?: ?string, +isViewer?: ?boolean, ... },
 ): ?string {
   const ethAddress = React.useMemo(() => {
     if (
diff --git a/lib/shared/user-utils.js b/lib/shared/user-utils.js
--- a/lib/shared/user-utils.js
+++ b/lib/shared/user-utils.js
@@ -5,17 +5,16 @@
 import type {
   ServerThreadInfo,
   RawThreadInfo,
-  RelativeMemberInfo,
   ThreadInfo,
 } from '../types/thread-types';
-import type {
-  RelativeUserInfo,
-  UserInfo,
-  UserInfos,
-} from '../types/user-types';
+import type { UserInfo, UserInfos } from '../types/user-types';
 import { memberHasAdminPowers } from './thread-utils';
 
-function stringForUser(user: RelativeUserInfo | RelativeMemberInfo): string {
+function stringForUser(user: {
+  +username?: ?string,
+  +isViewer?: ?boolean,
+  ...
+}): string {
   if (user.isViewer) {
     return 'you';
   }
@@ -23,9 +22,7 @@
   return stringForUserExplicit(user);
 }
 
-function stringForUserExplicit(
-  user: RelativeUserInfo | RelativeMemberInfo,
-): string {
+function stringForUserExplicit(user: { +username: ?string, ... }): string {
   if (user.username) {
     return user.username;
   } else {