diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -58,7 +58,6 @@
   type ComposableMessageInfo,
 } from '../types/message-types.js';
 import type {
-  MinimallyEncodedMemberInfo,
   MinimallyEncodedRawThreadInfo,
   MinimallyEncodedRelativeMemberInfo,
   MinimallyEncodedThreadCurrentUserInfo,
@@ -84,7 +83,7 @@
 import {
   type RawThreadInfo,
   type ThreadInfo,
-  type LegacyMemberInfo,
+  type MemberInfo,
   type ServerThreadInfo,
   type RelativeMemberInfo,
   type ThreadCurrentUserInfo,
@@ -278,10 +277,7 @@
 
 function threadActualMembers(
   memberInfos: $ReadOnlyArray<
-    | LegacyMemberInfo
-    | RelativeMemberInfo
-    | MinimallyEncodedMemberInfo
-    | MinimallyEncodedRelativeMemberInfo,
+    MemberInfo | RelativeMemberInfo | MinimallyEncodedRelativeMemberInfo,
   >,
 ): $ReadOnlyArray<string> {
   return memberInfos
@@ -290,11 +286,7 @@
 }
 
 function threadOtherMembers<
-  T:
-    | LegacyMemberInfo
-    | RelativeMemberInfo
-    | MinimallyEncodedMemberInfo
-    | MinimallyEncodedRelativeMemberInfo,
+  T: MemberInfo | RelativeMemberInfo | MinimallyEncodedRelativeMemberInfo,
 >(memberInfos: $ReadOnlyArray<T>, viewerID: ?string): $ReadOnlyArray<T> {
   return memberInfos.filter(
     memberInfo => memberInfo.role && memberInfo.id !== viewerID,
@@ -1139,8 +1131,7 @@
 function memberIsAdmin(
   memberInfo:
     | RelativeMemberInfo
-    | LegacyMemberInfo
-    | MinimallyEncodedMemberInfo
+    | MemberInfo
     | MinimallyEncodedRelativeMemberInfo,
   threadInfo:
     | ThreadInfo
@@ -1158,9 +1149,8 @@
 function memberHasAdminPowers(
   memberInfo:
     | RelativeMemberInfo
-    | LegacyMemberInfo
+    | MemberInfo
     | ServerMemberInfo
-    | MinimallyEncodedMemberInfo
     | MinimallyEncodedRelativeMemberInfo,
 ): boolean {
   if (memberInfo.minimallyEncoded) {
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -16,6 +16,7 @@
   RawMessageInfo,
 } from './message-types.js';
 import type {
+  MinimallyEncodedMemberInfo,
   MinimallyEncodedResolvedThreadInfo,
   MinimallyEncodedRoleInfo,
 } from './minimally-encoded-thread-permissions-types.js';
@@ -53,6 +54,8 @@
     isSender: t.Boolean,
   });
 
+export type MemberInfo = LegacyMemberInfo | MinimallyEncodedMemberInfo;
+
 export type RelativeMemberInfo = $ReadOnly<{
   ...LegacyMemberInfo,
   +username: ?string,