Four months after Ray J released a song that most assumed was about Kim Kardashian, Kanye West is firing back in defense of his baby mama.

While making a surprise appearance on "Late Night with Jimmy Fallon," the "Yeezus" rapper performed his new song "Bound 2."

Changing a few lyrics, Kanye took aim at "Brandy's little sister" declaring, he "was lame and he know it."

The slam is most likely referring to Ray's "I Hit It First" video which was released back in April. Check out West's performance in the player below!