McDonalds is testing Sweet Potato Fries in Texas

Well known for its signature "World Famous Fries", McDonald's is testing out a new spin on them, made with sweet potatoes.

Some 18 restaurants in the Amarillo, Texas, area are selling the new sweet potato fries.

Prices vary by restaurant. On average, they are selling for $2.49 for a 16-ounce size.

"Considering the fries are a test, they will be offered for a limited time as we gather feedback from our customers," said McDonald's spokeswoman Jeanette DeBartolo. "There is currently no plan to launch them nationally."