The purpose of this article is to show that when the half-life of a specimen being measured is comparable to the dead time of the measurement system, an additional correction is required in the classical dead-time correction formula for a nonparalyzing detector. This additional correction accounts for the decay of radioactivity during the dead time, and therefore the expression for the additional correction includes the specimen half-life. This additional correction is significant for some specialized applications involving very short-lived nuclides. These results may be useful for neutron activation analysis of short-lived isotopes and certain medical imaging applications.