diff --git a/include/hardware/sensors.h b/include/hardware/sensors.h
index 1d73c31..b1df317 100644
--- a/include/hardware/sensors.h
+++ b/include/hardware/sensors.h
@@ -1308,11 +1308,16 @@
         struct {
             struct hw_device_t common;
 
-            /* Activate/de-activate one sensor. Return 0 on success, negative
+            /* Activate/de-activate one sensor.
              *
              * sensor_handle is the handle of the sensor to change.
              * enabled set to 1 to enable, or 0 to disable the sensor.
              *
+             * After sensor de-activation, existing sensor events that have not
+             * been picked up by poll() should be abandoned immediately so that
+             * subsequent activation will not get stale sensor events (events
+             * that is generated prior to the latter activation).
+             *
              * Return 0 on success, negative errno code otherwise.
              */
             int (*activate)(struct sensors_poll_device_t *dev,