That's hot: Nicole Richie accidentally sets hair on fire at 40th birthday party

Nicole Richie posted the video on Instagram with the caption: 'Well... so far 40 is (fire emoji).' Photo: AFP

Nicole Richie welcomed her 40s with a birthday party that's simply unforgettable... for the wrong reason.

The actress-fashion designer turned 40 on Tuesday (Sept 21) and celebrated it with an outdoor party. As she was about to blow out the candles on her cake, her hair caught on fire!