Capybara, Ruby: Accessing attribute of found element with special characters in

Currently i am trying to get the content of an attribute of an capybara element in ruby. The attribute name is col-index. Now I want to access the attribute via

[:col-index]

The problem here is, that symbols don´t seem to accept characters like a - . What can I do different here? I cannot change the attribute name and I think it is a simple ruby issue.

If you need more code, just tell me. Thanks!