Using Jenkins BUILD NUMBER in RPM spec file

Name:                   My Software
Version:                1.0.5
Release:                1
Summary:                This is my software

Not sure if anyone has tried this before or if it is easy, but:

A spec file has two unique indicators for its version:

• Version (which specifies software version)
• Release (which specifies the package's number - if you build an RPM, it's broken, and build another one, you up the 'Release' number.

I'm wondering if anyone has tried, or knows how, I could use the Jenkins $BUILD_NUMBER variable to dynamically change the Release number, thereby increasing the Release number every time a new successful build completes...?