diff --git a/lib/types/minimally-encoded-thread-permissions-types.js b/lib/types/minimally-encoded-thread-permissions-types.js
--- a/lib/types/minimally-encoded-thread-permissions-types.js
+++ b/lib/types/minimally-encoded-thread-permissions-types.js
@@ -160,9 +160,14 @@
   +currentUser: ThreadCurrentUserInfo,
 }>;
 
+export type RawThreadInfoWithMemberPermissions = $ReadOnly<{
+  ...RawThreadInfo,
+  +members: $ReadOnlyArray<MemberInfoWithPermissions>,
+}>;
+
 const minimallyEncodeRawThreadInfo = (
   rawThreadInfo: LegacyRawThreadInfo,
-): RawThreadInfo => {
+): RawThreadInfoWithMemberPermissions => {
   invariant(
     !('minimallyEncoded' in rawThreadInfo),
     'rawThreadInfo is already minimally encoded.',