[en] We have limited a CPT-violating correlation in annihilations of polarized ortho-positronium. We searched for an asymmetry in the triple correlation s→·(k→₁xk→₂), where k→₁ and k→₂ are the two largest photon momenta, and s→ is the spin of the positronium. Using the Gammasphere array of Compton-suppressed high-purity germanium detectors, we detected 2.65x10⁷ events of ortho-Ps annihilation. The amplitude of a CPT-violating asymmetry in the data set is found to be 0.0026±0.0031, a factor of 6 smaller than previous experiments