A locking mechanism of an inertia reel assembly of a vehicular seatbelt restraint system is selectively disabled based on a latch status of a seatbelt buckle of the seatbelt restraint system. In one embodiment, a sensor at a latch assembly determines whether the seatbelt buckle is engaged with the latch assembly and provides an output signal based on this determination. A controller receives the output signal and selectively drives an actuator based on the output signal so as to enable or disable the locking mechanism of the inertia reel assembly. By disabling the locking mechanism of the inertia reel assembly when the seatbelt buckle is detected as unlatched, an occupant is able to quickly latch the seatbelt buckle even in the event of an inertial event that otherwise would have prevented any further extension of the seatbelt.