Why is_a? returns false for Hash class?

Question

Why is_a? returns false for a Hash class?

Example:

value = {"x" => 3, "y" => 2}

puts value.class
puts value.is_a?(Hash)

Output:

Hash
false

Im using Ruby 1.9.2

UPDATED: full source of my class:

class LatLng
  include Mongoid::Fields::Serializable

  attr_reader :lat, :lng

  def serialize(value)
    return if value.nil?

    puts value.class
    puts value.is_a?(Hash)

    if value.is_a?(self.class)
      puts "is geopoint" + value.to_json
      {'lng' => value.lng.to_f, 'lat' => value.lat.to_f}
    elsif value.is_a?(Hash)
      hash = value.with_indifferent_access
      puts "is hash" + value.to_json
      {'lng' => hash['lng'].to_f, 'lat' => hash['lat'].to_f}
    end
  end

  def deserialize(value)
    return if value.nil?

    value.is_a?(self.class) ? value : LatLng.new(value['lat'], value['lng'])
  end

  def initialize(lat, lng)
    @lat, @lng = lat.to_f, lng.to_f
  end

  def [](arg)
    case arg
      when "lat"
        @lat
      when "lng"
        @lng
    end
  end

  def to_a
    [lng, lat]
  end

  def ==(other)
    other.is_a?(self.class) && other.lat == lat && other.lng == lng
  end
end

Answer 1

#irb
ruby-1.9.3-p0 :001 > value = {"x" => 3, "y" => 2}
 => {"x"=>3, "y"=>2} 
ruby-1.9.3-p0 :002 > value.is_a?(Hash)
 => true

try to disable any gems/extensions you have loaded, and try with clean ruby

UPDATE:

try value.is_a?(::Hash)

PS: try to read about Duck Typing in Ruby. Maybe you should call value.respond_to?(:key) instead of value.is_a?(Hash)