Jamie Lynn Spears shared three throwback photos to mark the birthday of her older sister, Britney Spears.

The pop star turns 38 on Monday.

"When Britney got a perm, well I had to have one too (as pictured above)," Jamie Lynn Spears captioned her post. "Some things never change. Always looking up to you. Happy Birthday to my sister."

Britney Spears has not shared how she's celebrating her big day, but according to "Entertainment Tonight," the "I'm a Slave 4 U" singer is celebrating with her sons, Sean, 14, and Jayden, 13. According to a source, Spears is doing "incredibly well."

"She is trying to keep life simple and spend time with [her boyfriend] Sam [Asghari] and her kids whenever possible," the source told "ET."

"She plans to spend her birthday with her boys. She wants to just have a nice time with family."