Early-type stars possess ionized winds that produce detectable free-free emission in the radio band. Measurement of this thermal radiation was expected to provide a way to determine the stellar mass-loss rate. However, the observations have shown that these stars often have strong, time-variable nonthermal emission that contaminates the centimeter free-free radiation arising from the stellar wind. At higher frequencies, one expects to observe uncontaminated thermal emission. We present multifrequency radio continuum observations of a sample of eight 0 stars and Wolf-Rayet stars and propose that 7 mm radio observations are a more reliable method to derive mass-loss rates for massive stars. We also discuss how the 7 mm observations improve our knowledge of the characteristics of individual stars.