Khloe Kardashian has been given extra security after receiving an envelope containing a "mystery white powder".
The reality star, who hosts the US version of hit show X Factor alongside Mario Lopez, was said to be in "good spirits" after the scare.
"Khloe is fine," a source told E! News.
"The studio has hired extra security. Khloe is heading to rehearsals right now. She is not worried."
The substance was reportedly thoroughly tested by the FBI and came up "clean".
"The item was field-tested with negative results,” FBI Public Affairs Specialist Laura Eimiller said. “We have a continuing investigation."
Khloe tweeted a light-hearted "Awkward" in reference to the enigmatic envelope.