[steven_h]

It might have been when he initialized the variable result.

He goes on to append strings to this variable which would lead me to believe it has some value that you can append to.

This would make the third conditional where he checks for null to fail, he should check for an empty string.

[waffle_ss]

This is my conclusion as well. To wit, an approximate translation of his method into Ruby:

  fizzbuzz = (1..100).to_a.map do |i|
    result = "" # 1:23 initialize a variable
    result += "Fizz" if i % 3 == 0
    result += "Buzz" if i % 5 == 0
    result = i.to_s if result.nil?
    result
  end

The corrected solution would be to change `result.nil?` to `result.empty?`, i.e. checking for "empty string" instead of "null".