Illformed requirement error when installing gems

I'm getting the following error whenever I try to install any gem (sass as an example)

ERROR:  While executing gem ... (Gem::Requirement::BadRequirementError)
    Illformed requirement ["sass"]

I'm running Windows 10 Pro (not activated yet) so I was wondering if this could be a reason as to why this is happening? I've tried using the 32 bit version of Ruby 2.2.2 as well and it gives the same error. How do I fix this and what could be the reason I get it? Any help is appreciated, thanks!