Fixing the "this cannot include CR/LF" error when doing Basic auth in Ruby

Today, while testing an integration I'm currently working on for a client, I got the following error:

class: ArgumentError
message: header Authorization has field value "Basic somethingSomethingBase64Encoded", this cannot include CR/LF

This meant that my Authorization header was considered to be invalid, because it supposedly contained a new line character at the end, even though I certainly didn't recall adding any such thing when creating it.