X-ray powder diffraction data, unit cell parameters, and space group for alaptide are presented (a=21.136(4) Å, b=7.212(4) Å, c=6.126(3) Å, space group P212121, cell volume=933.8(8) Å3, and Z=4). All measured lines were indexed and are consistent with the P212121 space group. No detectable impurities were observed.