“That whole ordeal for me personally was terrifying,” says the actor about his concussion.

Norman Reedus knows a thing or two about traumatic injuries. In 2005, the actor was leaving an R.E.M. concert at the Berlin Film Festival (in a car provided by none other than Michael Stipe) when “We drove a few feet and just — BLOOSH!— an 18-wheeler went right through us,” Reedus told EW back in 2013. “I went out the window into the street unconscious. Woke up upside down with this big German lady wiping glass out of my face.”

Multiple operations — including the addition of a new titanium left-eye socket and four screws in his nose — left Reedus in such a state that “My whole head was like hamburger. It was just gnarly. I thought, ‘I’m never going to be an actor again. This is over.'”

Of course, his career was just getting stated — and after four months of recuperation, the actor was able to make his way back in front of a camera, and eventually to fame on The Walking Dead.

Norman Reedus stars as Daryl Dixon in ‘The Walking Dead’ final season. Jace Downs/AMC

But Reedus has not remained unscathed. This reporter alone has watched the man who plays Daryl Dixon get into his fair share of scrapes on set, including falling off his motorcycle and getting bandaged up after cutting his hand on a prop vending machine. His latest scare came during filming on The Walking Dead’s last ever episode.

On March 11, Reedus suffered a concussion on set while filming the finale. The injury pushed back shooting a few days — and a stand-in double was used for some scenes in which Daryl would not appear on camera. “Norman suffered a concussion on set,” read a statement from Reedus’ publicity rep after the incident. “He is recovering well and will return to work soon. Thank you to everyone for their concern.”

While reports of the injury did not make it out to be anything serious at the time, Reedus spoke to EW for our upcoming Walking Dead Fall TV Preview cover story, and now reveals it was actually much worse than originally disclosed. “Oh dude, that was horrible,” says the actor. “That whole ordeal for me personally was terrifying. I thought I was going to die.”

Even compared to Reedus’ near-death experience in Berlin, this latest head injury was especially traumatic. “It was very serious. It was scary. I’ve been hit in the face and the head a million times. I’ve gone through car windows, but that one rung my bell.”

Norman Reedus as Daryl Dixon on ‘The Walking Dead’. Jace Downs/AMC

The actor recalls a battery of tests and precautions put into place after the incident. “I had a neurologist. I had all sorts of s—. I failed the light test. I had a security guard in the driveway, just in case. I was holding onto the walls walking through the rooms. It was nuts.”

Reedus’ already precarious position was certainly exacerbated by his rough and tumble medical history. “I have headaches already because I have a metal eye socket and light sometimes affects me in weird ways,” notes the fan favorite. “I’m sitting in the dark right now. And then you download every calming app you can possibly find, you’re listening to crickets on your phone, and waterfalls, but then you have the ringer off so nobody can really get in touch with you because they’re like, ‘Do not answer your phone. Do not watch television. Just sit in the dark.’ And I’m listening to waterfalls and rain. I did listen to the New York City rain app a lot.”

As if worrying about his own health after the injury was not tough enough, Reedus was also concerned how his absence from the set was impacting production, which already had an elongated filming schedule due to the 24-episode final season. “You’re shooting over a year, and now we’re having to postpone some of the shooting because I’m lying in bed,” So the guilt of me not being at work and people are like, ‘Are we going to go a week over? Are we going two weeks over?’ — that was bothering me.”

Thankfully, the actor was able to get back to set both hearty and healthy and complete filming on the finale, which will air Nov. 20 on AMC.

For more scoop on the franchise, keep an eye out for The Walking Dead gracing the cover of EW’s Fall TV Preview package, coming this Thursday, Sept. 8.