Ruby 1.8 to 1.9 was a major version change in the semver sense; Ruby wasn't using Semver before, IIRC, 2.1.0, it was using a scheme that was basically loosely like Semver with an extra prefix number. Ruby minor versions were equivalent semver major (and also had a less-stable implication for odd numbers, more stable for even, Ruby “tiny” versions were equivalent to semver minor, and Ruby still had patch versions.