ZE:A's Kwanghee wished his fellow 'Infinity Challenge' co-star Yoo Jae Suk a happy birthday with a serenade!

SEE ALSO: Min Hee Jin claims BTS, TWS, and RIIZE copied her Concepts

The "nation's MC" turned 44 on August 14, and Kwanghee made sure to congratulate him. He posted to Instagram, "Happy birthday to Jaesuk hyung," and shared a video clip with firework effects and his own personal serenade.

You can check out Kwanghee's post as well as his song to Yoo Jae Suk below!