Scores with mixed stave sizes - how to create uniform barlines?

I have a score with a mixture of large and small staves. How can I get the same thickness / size of barline across both sizes of stave? Having a mixture of barline thicknesses looks rubbish, especially for a small stave that's joined vertically to other staves, and even more so for a final barline! I've tinkered with the Inspector, looked for a solution online etc., but can't find one. Help!

Screenshot attached.