Commented Unassigned: SCSS Class names that end with hyphen number [95]

I get a
```
undefined method `+' for nil:NilClass
```
when I try to
```
@extend .heading-6;
```
Is there a way to force that to be evaluated as a name and not a formula? I've tried using .heading-#{'6'} to the same outcome. If forced, I can change the class name, but would prefer to keep it as is.
Comments: I just updated to 1.9.48 and am still getting this error. I found one cause of this error. Not sure if this is valid scss since this is my first time looking at it (taking this over from a designer). It compiles fine using Web Workbench, but fails using the transform. This is the basic SCSS: .slide { } .cycle-slideshow .slide { @extend .slide; height: 100vh; } and my bundleconfig has: BundleTransformer.Core.Bundles.CustomStyleBundle sb2 = new BundleTransformer.Core.Bundles.CustomStyleBundle("~/bundles/styletest"); sb2.Include("~/styles/scss1.scss"); bundles.Add(sb2);