Simon Cowell has spent £100 000 turning his home into a "fortress".
The music mogul has splashed out the huge sum improving security on his London house after a fan was able to break in and hide in his wardrobe earlier this year.
A source told The Sun newspaper: "Simon's a perfectionist about everything and his security renovations were so extensive he's had to put in for planning permission to get them done.
"He basically wants to transform his London home into a fortress."
Simon previously admitted he had to hide from Leanne Zaloumis - who was reportedly found in the bathroom with half a brick above her head and her hands drenched in blood - when she broke in during March.
He said: "I ended up hiding in one of my wardrobe closets until the police found her. That was a little spooky."
After hearing a "loud bang" when the intruder crashed through the window when he was watching television in his home, Simon alerted his staff, who in turn called the cops and sent a squad of armed officers to the property.
Zaloumis was then found hiding on a shelf seven feet off the ground in a walk-in wardrobe.
The intruder appeared in court in August to be sentenced for the break-in.
She was handed a 12-month community order with a mental health requirement.
She has also been ordered to stay away from Simon under a restraining order, while she must also wear an electronic tag and adhere to a strict curfew.