Scala: how to get random element form given list

I want to pick random element from given list:

  def randomAlphaNumericChar(): Char = {
    val ALPHA_NUMERIC_STRING = "aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ0123456789".toCharArray
    Gen.oneOf(ALPHA_NUMERIC_STRING)
  }

So currently this now compile:

type mismatch; found : org.scalacheck.Gen[Char] required: Char Gen.oneOf(ALPHA_NUMERIC_STRING)