2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/166367We report on a problem found in MERCURY, a hybrid symplectic integrator used for dynamical problems in Astronomy. The variable that keeps track of bodies' statuses is uninitialised, which can result in bodies disappearing from simulations in a non-physical manner. Some FORTRAN compilers implicitly initialise variables, preventing simulations from having this problem. With other compilers, simulations with a suitably large maximum number of bodies parameter value are also unaffected. Otherwise, the problem manifests at the first event after the integrator is started, whether from scratch or continuing a previously stopped simulation. Although the problem does not manifest in some conditions, explicitly initialising the variable solves the problem in a permanent and unconditional manner.4 pages, 2 figures, 1 tableAstrophysicstext