The current invention mitigates the problem of incorrect determinations of leaking packages during vacuum decay leak detection testing. As described in this disclosure, a testing chamber used for vacuum decay leak detection testing is exposed to interferences when not under vacuum or at low pressure conditions between testing cycles. By measuring one or more exposure time intervals immediately preceding a present test cycle, it is possible to improve detection of leaking packages by adjusting raw measured pressure gathered during vacuum decay leak testing based upon the length of exposure times and create corrected pressure data used to improve vacuum decay leak detection.