An ankle brace comprising a base of flexible material shaped to wrap around the sides of a foot and ankle and underneath a portion of the foot, with a support strap for protecting the anterior talofibular ligament. The two ends of the support strap are fixed to the base at or near the forward edges of the base. The strap is not otherwise fixed to the base underneath the sole of the foot, allowing the strap to move freely under the foot to conform to the particular size and shape of the foot of a particular wearer. The ankle brace features a symmetric construction which allows the ankle brace to be worn on either the left or the right foot, simplifying manufacturing and inventory management.