Using Uint8Array as an Argument for mutation in typegraphql

I need to save a public key to my postgres database from graphql. Using a Uint8Array seems the best option to save this with (let me know if you have a better suggestion). Therefore I have the entity:

@ObjectType()
@Entity()
export class Wallet extends BaseEntity {
  @Field()
  @PrimaryGeneratedColumn()
  id!: number;

  @Field()
  @Column({ type: 'bytea' })
  public_key!: Uint8Array;
}

And the resolver:

  @Mutation(() => User)
  async createUser(

    @Arg("email") email: string,
    @Arg("wallets", _type => [Uint8Array], { nullable: true }) wallets: Uint8Array[],
    @Ctx() { em }: MyContext
  ): Promise<User> {
    // input validation

    const user = {
      email: email,
      wallets: (wallets ? wallets.map(e => ({ 'public_key': e })) : [])
    }
    return { user: await em.save(User, user) };
  }

CannotDetermineGraphQLTypeError: Cannot determine GraphQL input type for argument named 'wallets' of 'createUser' of 'UserResolver' class. Is the value, that is used as its TS type or explicit type, decorated with a proper decorator or is it a proper input value?

I'm not sure I understand this error properly, can I not use Uint8Array as an input to my mutation or am I doing it incorrectly?