Validation error for self-relation

[ymc9]

model User {
  id Int @id @default(autoincrement())
  email String @unique
  name String?
  manager User? @relation("UserToUser_managerId", fields: [managerId], references: [id])
  managerId Int?
}

Error:

Validation errors:
line 14: "fields" and "references" must be provided only on one side of relation field [manager User? @relation("UserToUser_managerId", fields: [managerId], references: [id])]