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
@@ -91,7 +91,6 @@
 import type {
   LegacyRawThreadInfo,
   LegacyRoleInfo,
-  MemberInfo,
   ServerThreadInfo,
   ServerMemberInfo,
   ClientNewThreadRequest,
@@ -219,17 +218,18 @@
 }
 
 function threadActualMembers(
-  memberInfos: $ReadOnlyArray<MemberInfo | RelativeMemberInfo>,
+  memberInfos: $ReadOnlyArray<
+    LegacyMemberInfo | MinimallyEncodedMemberInfo | RelativeMemberInfo,
+  >,
 ): $ReadOnlyArray<string> {
   return memberInfos
     .filter(memberInfo => memberInfo.role)
     .map(memberInfo => memberInfo.id);
 }
 
-function threadOtherMembers<T: MemberInfo | RelativeMemberInfo>(
-  memberInfos: $ReadOnlyArray<T>,
-  viewerID: ?string,
-): $ReadOnlyArray<T> {
+function threadOtherMembers<
+  T: LegacyMemberInfo | MinimallyEncodedMemberInfo | RelativeMemberInfo,
+>(memberInfos: $ReadOnlyArray<T>, viewerID: ?string): $ReadOnlyArray<T> {
   return memberInfos.filter(
     memberInfo => memberInfo.role && memberInfo.id !== viewerID,
   );
@@ -1030,7 +1030,11 @@
 // Since we don't have access to all of the ancestor ThreadInfos, we approximate
 // "parent admin" as anybody with CHANGE_ROLE permissions.
 function memberHasAdminPowers(
-  memberInfo: RelativeMemberInfo | MemberInfo | ServerMemberInfo,
+  memberInfo:
+    | RelativeMemberInfo
+    | LegacyMemberInfo
+    | MinimallyEncodedMemberInfo
+    | ServerMemberInfo,
 ): boolean {
   if (memberInfo.minimallyEncoded) {
     return hasPermission(memberInfo.permissions, threadPermissions.CHANGE_ROLE);
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
@@ -15,7 +15,6 @@
   RawMessageInfo,
 } from './message-types.js';
 import type {
-  MinimallyEncodedMemberInfo,
   RawThreadInfo,
   ResolvedThreadInfo,
   ThreadInfo,
@@ -51,8 +50,6 @@
     isSender: t.Boolean,
   });
 
-export type MemberInfo = LegacyMemberInfo | MinimallyEncodedMemberInfo;
-
 export type LegacyRoleInfo = {
   +id: string,
   +name: string,