Install Firefox Redirector: https://addons.mozilla.org/en-US/firefox/addon/redirector/
Add a rule to redirect (https?://)?(\w+\.)m\.wikipedia.org(.*) to $1$2wikipedia.org$3
Then you never have to deal with mobile Wikipedia on desktop again. You can use this for other sites too, like forcing all uses of Reddit to always open in old.reddit.com.