diff --git a/packages/backend/src/core/CustomEmojiService.ts b/packages/backend/src/core/CustomEmojiService.ts
index 0f26d22666..de9b748f4d 100644
--- a/packages/backend/src/core/CustomEmojiService.ts
+++ b/packages/backend/src/core/CustomEmojiService.ts
@@ -13,6 +13,7 @@ import { MemoryKVCache, RedisSingleCache } from '@/misc/cache.js';
 import { UtilityService } from '@/core/UtilityService.js';
 import type { Config } from '@/config.js';
 import { query } from '@/misc/prelude/url.js';
+import { Serialized } from '@/server/api/stream/types';
 
 @Injectable()
 export class CustomEmojiService {
@@ -46,7 +47,7 @@ export class CustomEmojiService {
 			toRedisConverter: (value) => JSON.stringify(Array.from(value.values())),
 			fromRedisConverter: (value) => {
 				if (!Array.isArray(JSON.parse(value))) return undefined; // 古いバージョンの壊れたキャッシュが残っていることがある(そのうち消す)
-				return new Map(JSON.parse(value).map((x: Emoji) => [x.name, {
+				return new Map(JSON.parse(value).map((x: Serialized<Emoji>) => [x.name, {
 					...x,
 					updatedAt: x.updatedAt && new Date(x.updatedAt),
 				}]));
diff --git a/packages/backend/src/server/api/stream/types.ts b/packages/backend/src/server/api/stream/types.ts
index 101f6bf261..d9dba682cd 100644
--- a/packages/backend/src/server/api/stream/types.ts
+++ b/packages/backend/src/server/api/stream/types.ts
@@ -172,7 +172,7 @@ type EventUnionFromDictionary<
 > = U[keyof U];
 
 // redis通すとDateのインスタンスはstringに変換されるので
-type Serialized<T> = {
+export type Serialized<T> = {
 	[K in keyof T]:
 		T[K] extends Date
 			? string