Apple co-founder Steve Wozniak was hospitalized in Mexico City on Wednesday due to a possible stroke, Mexican media outlets reported, but a TMZ report citing sources suggested the illness was potentially a less serious bout of vertigo.

The 73-year-old scientist and tech entrepreneur was scheduled to participate in a World Business Forum event in the Mexican capital’s Santa Fe neighborhood on Wednesday afternoon

Event organizers did not immediately respond to a request for comment.

Wozniak had been set to speak at the conference at 4:20 p.m. local time.

Reuters could not immediately confirm the reports that Wozniak had been hospitalized.

U.S. media outlet TMZ, citing sources with direct knowledge, reported that Wozniak finished his speech but then told his wife he was “feeling strange.”

She reportedly insisted he go to the hospital.

The TMZ report said Wozniak may have suffered vertigo.

In the 1976, Wozniak founded the fledgling Apple Computer company along with his more famous business partner Steve Jobs, the acclaimed investor and longtime Apple CEO who died in 2011.

Their business pioneered personal computing and went on to be the world’s most valuable company, known for the design and functionality of a range of consumer electronics, including laptop and desktop computers, and the iPhone mobile phone.

Individuals affiliated with Wozniak’s website woz.org did not immediately respond to a request for comment.