diff --git a/lib/types/messages/change-role.js b/lib/types/messages/change-role.js
--- a/lib/types/messages/change-role.js
+++ b/lib/types/messages/change-role.js
@@ -16,10 +16,10 @@
   +roleName?: string, // Older clients will not have this field
 };
 
-export type RawChangeRoleMessageInfo = {
+export type RawChangeRoleMessageInfo = $ReadOnly<{
   ...ChangeRoleMessageData,
   +id: string,
-};
+}>;
 
 export const rawChangeRoleMessageInfoValidator: TInterface<RawChangeRoleMessageInfo> =
   tShape<RawChangeRoleMessageInfo>({
diff --git a/lib/types/messages/edit.js b/lib/types/messages/edit.js
--- a/lib/types/messages/edit.js
+++ b/lib/types/messages/edit.js
@@ -15,10 +15,10 @@
   +text: string,
 };
 
-export type RawEditMessageInfo = {
+export type RawEditMessageInfo = $ReadOnly<{
   ...EditMessageData,
   +id: string,
-};
+}>;
 
 export const rawEditMessageInfoValidator: TInterface<RawEditMessageInfo> =
   tShape<RawEditMessageInfo>({
diff --git a/lib/types/messages/media.js b/lib/types/messages/media.js
--- a/lib/types/messages/media.js
+++ b/lib/types/messages/media.js
@@ -16,15 +16,15 @@
   +media: $ReadOnlyArray<Media>,
 };
 
-export type MediaMessageData = {
+export type MediaMessageData = $ReadOnly<{
   ...MediaSharedBase,
   +sidebarCreation?: boolean,
-};
+}>;
 
-export type RawMediaMessageInfo = {
+export type RawMediaMessageInfo = $ReadOnly<{
   ...MediaSharedBase,
   +id?: string, // null if local copy without ID yet
-};
+}>;
 
 export const rawMediaMessageInfoValidator: TInterface<RawMediaMessageInfo> =
   tShape<RawMediaMessageInfo>({
diff --git a/lib/types/messages/reaction.js b/lib/types/messages/reaction.js
--- a/lib/types/messages/reaction.js
+++ b/lib/types/messages/reaction.js
@@ -17,10 +17,10 @@
   +action: 'add_reaction' | 'remove_reaction',
 };
 
-export type RawReactionMessageInfo = {
+export type RawReactionMessageInfo = $ReadOnly<{
   ...ReactionMessageData,
-  id?: string, // null if local copy without ID yet
-};
+  +id?: string, // null if local copy without ID yet
+}>;
 
 export const rawReactionMessageInfoValidator: TInterface<RawReactionMessageInfo> =
   tShape<RawReactionMessageInfo>({
diff --git a/lib/types/messages/toggle-pin.js b/lib/types/messages/toggle-pin.js
--- a/lib/types/messages/toggle-pin.js
+++ b/lib/types/messages/toggle-pin.js
@@ -16,10 +16,10 @@
   +time: number,
 };
 
-export type RawTogglePinMessageInfo = {
+export type RawTogglePinMessageInfo = $ReadOnly<{
   ...TogglePinMessageData,
   +id: string,
-};
+}>;
 
 export const rawTogglePinMessageInfoValidator: TInterface<RawTogglePinMessageInfo> =
   tShape<RawTogglePinMessageInfo>({
diff --git a/lib/types/messages/unsupported.js b/lib/types/messages/unsupported.js
--- a/lib/types/messages/unsupported.js
+++ b/lib/types/messages/unsupported.js
@@ -2,6 +2,30 @@
 
 import t, { type TInterface } from 'tcomb';
 
+import {
+  rawChangeRoleMessageInfoValidator,
+  type RawChangeRoleMessageInfo,
+} from './change-role.js';
+import {
+  rawEditMessageInfoValidator,
+  type RawEditMessageInfo,
+} from './edit.js';
+import {
+  rawMediaMessageInfoValidator,
+  type RawMediaMessageInfo,
+} from './media.js';
+import {
+  rawReactionMessageInfoValidator,
+  type RawReactionMessageInfo,
+} from './reaction.js';
+import {
+  rawTogglePinMessageInfoValidator,
+  type RawTogglePinMessageInfo,
+} from './toggle-pin.js';
+import {
+  rawUpdateFarcasterRelationshipMessageInfoValidator,
+  type RawUpdateFarcasterRelationshipMessageInfo,
+} from './update-relationship.js';
 import { tID, tNumber, tShape } from '../../utils/validation-utils.js';
 import { messageTypes } from '../message-types-enum.js';
 import type { RelativeUserInfo } from '../user-types.js';
@@ -14,7 +38,13 @@
   time: number,
   robotext: string,
   dontPrefixCreator?: boolean,
-  unsupportedMessageInfo: Object,
+  unsupportedMessageInfo:
+    | RawUpdateFarcasterRelationshipMessageInfo
+    | RawChangeRoleMessageInfo
+    | RawEditMessageInfo
+    | RawMediaMessageInfo
+    | RawReactionMessageInfo
+    | RawTogglePinMessageInfo,
 };
 
 export const rawUnsupportedMessageInfoValidator: TInterface<RawUnsupportedMessageInfo> =
@@ -26,7 +56,17 @@
     time: t.Number,
     robotext: t.String,
     dontPrefixCreator: t.maybe(t.Boolean),
-    unsupportedMessageInfo: t.Object,
+    unsupportedMessageInfo: t.union([
+      // We include these validators here to make sure that the keyserver does
+      // ID conversion on unsupportedMessageInfo when it's one of these types
+      rawUpdateFarcasterRelationshipMessageInfoValidator,
+      rawChangeRoleMessageInfoValidator,
+      rawEditMessageInfoValidator,
+      rawMediaMessageInfoValidator,
+      rawReactionMessageInfoValidator,
+      rawTogglePinMessageInfoValidator,
+      t.Object,
+    ]),
   });
 
 export type UnsupportedMessageInfo = {
@@ -37,5 +77,11 @@
   time: number,
   robotext: string,
   dontPrefixCreator?: boolean,
-  unsupportedMessageInfo: Object,
+  unsupportedMessageInfo:
+    | RawUpdateFarcasterRelationshipMessageInfo
+    | RawChangeRoleMessageInfo
+    | RawEditMessageInfo
+    | RawMediaMessageInfo
+    | RawReactionMessageInfo
+    | RawTogglePinMessageInfo,
 };
diff --git a/lib/types/messages/update-relationship.js b/lib/types/messages/update-relationship.js
--- a/lib/types/messages/update-relationship.js
+++ b/lib/types/messages/update-relationship.js
@@ -36,10 +36,19 @@
   | UpdateTraditionalRelationshipMessageData
   | UpdateFarcasterRelationshipMessageData;
 
-export type RawUpdateRelationshipMessageInfo = {
-  ...UpdateRelationshipMessageData,
-  id: string,
-};
+export type RawUpdateTraditionalRelationshipMessageInfo = $ReadOnly<{
+  ...UpdateTraditionalRelationshipMessageData,
+  +id: string,
+}>;
+
+export type RawUpdateFarcasterRelationshipMessageInfo = $ReadOnly<{
+  ...UpdateFarcasterRelationshipMessageData,
+  +id: string,
+}>;
+
+export type RawUpdateRelationshipMessageInfo =
+  | RawUpdateTraditionalRelationshipMessageInfo
+  | RawUpdateFarcasterRelationshipMessageInfo;
 
 export const rawUpdateTraditionalRelationshipMessageInfoValidator: TInterface<RawUpdateRelationshipMessageInfo> =
   tShape<RawUpdateRelationshipMessageInfo>({