James Martin/CNET

Apple co-founder Steve Wozniak has a warning for Tim Cook and his executives: stay cool, or you'll have trouble.

Speaking to Bloomberg in an interview published today, Wozniak said that while Apple is still "really good at setting a standard with a new device," it's starting to lose its standing as the coolest company in the technology industry.

"We used to have these ads, 'I'm a Mac and I'm a PC,' and the Mac was always the cool guy," Wozniak told Bloomberg. "And ouch, it's painful, because we kind of are losing that."

According to Bloomberg, Wozniak said that Apple's products are no longer able to easily trump competing devices from Amazon and Google because those companies "all have great ideas." He added that Apple should at least consider opening iTunes to Android and Windows Phone users.

Wozniak has been surprisingly outspoken about Apple over the last several months. In October, he called the company "arrogant" and lamented that it believed it was "the only one with the right clue." In November, he said that he was worried that Apple is "just used to cranking out the newest iPhone and falling a little behind." He also took a jab at the late Steve Jobs, saying that he didn't have "to be as much of a real rugged bastard, put people down, and make them feel demeaned."

Despite the negative talk, Wozniak told Bloomberg that he was hoping Apple would launch the rumored iWatch -- a device, he said, he would definitely buy.