diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index f2dc6d8fc680..38a993508327 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -54,7 +54,8 @@ struct ptp_clock_request {
  * clock operations
  *
  * @adjfreq:  Adjusts the frequency of the hardware clock.
- *            parameter delta: Desired period change in parts per billion.
+ *            parameter delta: Desired frequency offset from nominal frequency
+ *            in parts per billion
  *
  * @adjtime:  Shifts the time of the hardware clock.
  *            parameter delta: Desired change in nanoseconds.