How do I use <b> in XML when I have a custom font? (Android Studio)

I have added Helvetica Neue Thin as a custom font. Previously I had just a standard system font. In my XML I mark my strings with <b>text</b> to set certain parts as bold. This worked fine using the system font. But now that I have imported a custom font, Android Studio no longer knows what font to use as a bold alternative, leaving all the <b> marked text as Helvetica Neue Thin.

How do I tell Android Studio to use the Helvetica bold font that I have also imported? I guess I have to place them in the same font family or something... Any ideas?