House Rule: Minor Spellcasting

I've been using a house rule in 5e right from the start without ever really mentioning it. I call it the "Minor Spellcasting Rule" - both because it relates to minor spellcasting and because it's a pretty minor rule.

There are several ways that a character can gain the ability to gain a small number of spells that are not directly associated with the characters class(es): the high elf, forest gnome, and tiefling races all grant one or more spells; and the magic initiate feat likewise. (And, of course, other means have been added in books after the PHB. Each of these means specifies a spellcasting ability for the spells granted.

The "Minor Spellcasting Rule" is a fairly small bit of tidying up: if you are a member of a spellcasting class and you also gain minor spellcasting via your race, a feat, or some other means, your spellcasting ability for the minor spellcasting is the same as for your class.

(For multiclass characters there are two additional considerations. Firstly, if you have two spellcasting classes and also gain minor spellcasting from somewhere else, you can choose which of your class spellcasting abilities to use. Secondly, if you have a spellcasting class and also a non-spellcasting class that grants some form of minor spellcasting, the Minor Spellcasting Rule applies - that is, the minor spellcasting from your non-spellcasting class uses the spellcasting ability from your spellcasting class. But then, I don't actually use multiclassing, so this is just listed for completeness.)