Limitation range for optional parameters

[SihirliDev]

Hello,

I have configured my routes under routes/($lang) folder.

Now I can access my site at www.mysite.com/en/.... or www.mysite.com/de/....

However it also responds to anything other than locales as expected like www.mysite.com/blablabla

Is there a workaround to limit the lang parameter only for these two languages and throw a 404 otherwise?

Thank you!