The phase shift of long-wavelength modes due to drift-wave turbulence is studied in the Hasegawa–Mima model. Although the growth rate has been the main focus, it is equally crucial to understand the frequency shift from the linear characteristics. The test-field model is applied in order to properly treat the sweeping effect of the large scales on a small scale. The frequency shift is found to be small compared with the growth rate and the non-local triad mode-interaction time turns out to be determined by the energy of the long-wavelength modes.