  General relativity (GR) is the current description of gravity in modern
physics. One of the cornerstones of GR, as well as Newton's theory of gravity,
is the weak equivalence principle (WEP), stating that the trajectory of a
freely falling test body is independent of its internal structure and
composition. WEP is known to be valid for the normal matter with a high
precision. However, due to the rarity of antimatter and weakness of the
gravitational forces, the WEP has never been confirmed for antimatter. The
current direct bounds on the ratio between the gravitational and inertial
masses of the antihydrogen do not rule out a repulsive nature for the
antimatter gravity. Here we establish an indirect bound of 0.13% on the
difference between the gravitational and inertial masses of the positron
(antielectron) from the analysis of synchrotron losses at the Large
Electron-Positron collider (LEP). This serves as a confirmation of the
conventional gravitational properties of antimatter without common assumptions
such as, e.g., coupling of gravity to virtual particles, dynamics of distant
astrophysical sources and the nature of absolute gravitational potentials.
