A 22-year-old woman with a history of headaches underwent brain imaging to exclude structural causes of headache. After magnetic resonance angiography suggested a basilar artery aneurysm, she was referred to our institution for further diagnostic workup. A conventional angiogram was performed and showed a possible aneurysm of the midbasilar segment (Figure A, arrow). Three-dimensional reconstructed images, however, demonstrated that this abnormality was clearly a fenestrated basilar artery without aneurysm. The image simulated an “ok” hand sign (Figure B, arrow) and no further intervention was taken.