Any way to draw this treads closer to risers?

[patrad]

I'm refinishing some really old stairs. (1896)

Any ideas on how to close these gaps between riser and tread? I don't have access to the underside.

 

[bud16415]

Welcome to the forum.

A lot of them had a quarter round in that corner. that closes the gap but still allows for expansion/contraction.

 

[patrad]

Thanks. More trim it is!