diff --git a/packages/backend/src/core/CustomEmojiService.ts b/packages/backend/src/core/CustomEmojiService.ts
index 0a7ee4b9c9..dc365986fe 100644
--- a/packages/backend/src/core/CustomEmojiService.ts
+++ b/packages/backend/src/core/CustomEmojiService.ts
@@ -45,6 +45,7 @@ export class CustomEmojiService {
 			fetcher: () => this.emojisRepository.find({ where: { host: IsNull() } }).then(emojis => new Map(emojis.map(emoji => [emoji.name, emoji]))),
 			toRedisConverter: (value) => JSON.stringify(value.values()),
 			fromRedisConverter: (value) => {
+				// 原因不明だが配列以外が入ってくることがあるため
 				if (!Array.isArray(JSON.parse(value))) return undefined;
 				return new Map(JSON.parse(value).map((x: Emoji) => [x.name, x]));
 			}, // TODO: Date型の変換