diff --git a/packages/backend/src/server/api/endpoints/drive/files/update.ts b/packages/backend/src/server/api/endpoints/drive/files/update.ts
index d113b978f..e681f1294 100644
--- a/packages/backend/src/server/api/endpoints/drive/files/update.ts
+++ b/packages/backend/src/server/api/endpoints/drive/files/update.ts
@@ -54,7 +54,7 @@ export const paramDef = {
 		folderId: { type: "string", format: "misskey:id", nullable: true },
 		name: { type: "string" },
 		isSensitive: { type: "boolean" },
-		comment: { type: "string", nullable: true, maxLength: 512 },
+		comment: { type: "string", nullable: true, maxLength: DB_MAX_IMAGE_COMMENT_LENGTH },
 	},
 	required: ["fileId"],
 } as const;