Gwen Stefani shows off her natural hair color in throwback photo on Instagram

Gwen Stefani is showing her roots.

Most fans know the 50-year-old musician for her bright blonde hair, be it long, short, curled, straightened or anything in between -- but on Wednesday, the singer reminded the world that she hasn't always looked that way.

In a throwback picture in honor of her brother Eric's birthday, a back-in-the-day Stefani could be seen sporting light brown hair, which extended just past her shoulders.

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She also wore a sleeveless white dress while she held up a cake with candles in front of her brother.

"Happy b day @ericstefanimation #ericstefani," she wrote in the caption. "I wouldn’t be me w out u! love u!!!"

In the photo, Eric's mouth is open wide, prepared to blow out the numerous candles on the cake.

While many fans wished Stefani's brother happy birthday in the comments section, others couldn't help but notice the star's brunette hue.

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"Bring Back Brunette!" one person wrote, while another agreed: "I was thinking the same. She looked good as brunette. Any color actually."

"I love your dark hair!! Soooo cute!!" said another person. "Can you have this hair colour again please," asked another commenter.

Although pictures of her platinum blonde 'do are much more common, the "Hollaback Girl" singer has shown off pics featuring her natural hair on Instagram before.

This time last year, in celebration of Father's Day, Stefani shared another throwback of herself standing with her father and younger sister, Jill.

In the photo, no doubt about it, little Stefani had dark brown hair, as did her dad and sister.

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"Happy Father’s Day to one of my favorite humans I know ..." she wrote in the photo's caption. "Always there for me and my boys I love [you with] all my heart."