  Using recently established empirical calibrations for the impact of
chromospheric activity on the radii, effective temperatures, and estimated
masses of active low-mass stars and brown dwarfs, we reassess the shape of the
initial mass function (IMF) across the stellar/substellar boundary in the Upper
Sco star-forming region (age 5-10 Myr). We adjust the observed effective
temperatures to warmer values using the observed strength of the chromospheric
H$\alpha$ emission, and redetermine the estimated masses of objects using
pre--main-sequence evolutionary tracks in the H-R diagram. The effect of the
activity-adjusted temperatures is to shift the objects to higher masses by
3-100%. While the slope of the resulting IMF at substellar masses is not
strongly changed, the peak of the IMF does shift from ~0.06 to ~0.11 Msun.
Moreover, for objects with masses <~0.2 Msun, the ratio of brown dwarfs to
stars changes from ~80% to ~33%. These results suggest that activity
corrections are essential for studies of the substellar mass function, if the
masses are estimated from spectral types or from effective temperatures.
