"Happy birthday to this magic human, I love you!!!!" Cabello wrote in the caption of the pic, which is a lo-fi polaroid that shows Mendes playing with her hair.
The two "Señorita" singers have had a lengthy relationship dating back to 2014 when they both opened for Austin Mahone on tour. Most recently, they collaborated on their heated single, which came with an equally spicy video, and were spotted having a PDA-filled weekend in San Francisco just last month, though neither has spoken publicly about their relationship status.
See the cute post below.