EXCLUSIVE

Deadmau5 is now in a legal brawl with Disney over whether his famous headgear is too similar to its logo -- but the DJ says the Mouse House hasn't made a squeak about this for a decade.

In documents filed Tuesday ... Disney claims Deadmau5's logo is too similar to their famous Mickey ears, and they're trying to block him from getting a trademark in the U.S.

Of course, Deadmau5 has been wearing his mouse head costume for 10 years now -- and his attorney Dina LaPolt tells TMZ he already has a trademark for it in 30 other countries ... including Japan, Germany, Italy and the U.K.

Deadmau5 applied through the U.S. Patent and Trademark Office last year.

In the docs, Disney states its ears have been a thing for more than 60 years, and says granting Deadmau5 the trademark would damage its business in the U.S. and around the world.