diff --git a/src/schemas/activitypub.ts b/src/schemas/activitypub.ts
index 513457d9..f14c994f 100644
--- a/src/schemas/activitypub.ts
+++ b/src/schemas/activitypub.ts
@@ -154,16 +154,6 @@ const objectSchema = z.union([
   ]),
 );
 
-/** https://docs.joinmastodon.org/entities/Instance/#thumbnail */
-const thumbnailSchema = z.object({
-  url: z.string().url(),
-  blurhash: z.string().optional(),
-  versions: z.object({
-    '@1x': z.string().url().optional(),
-    '@2x': z.string().url().optional(),
-  }).optional(),
-});
-
 const createNoteSchema = z.object({
   type: z.literal('Create'),
   id: apId,
@@ -328,7 +318,6 @@ export type {
   Note,
   Object,
   Proxy,
-  thumbnailSchema,
   Update,
   Zap,
 };
diff --git a/src/schemas/mastodon.ts b/src/schemas/mastodon.ts
new file mode 100644
index 00000000..bedd1aad
--- /dev/null
+++ b/src/schemas/mastodon.ts
@@ -0,0 +1,13 @@
+import { z } from 'zod';
+
+/** https://docs.joinmastodon.org/entities/Instance/#thumbnail */
+const thumbnailSchema = z.object({
+  url: z.string().url(),
+  blurhash: z.string().optional(),
+  versions: z.object({
+    '@1x': z.string().url().optional(),
+    '@2x': z.string().url().optional(),
+  }).optional(),
+});
+
+export { thumbnailSchema };