diff --git a/include/uapi/linux/ptp_clock.h b/include/uapi/linux/ptp_clock.h
index 9a0af3511b682..f16301015949e 100644
--- a/include/uapi/linux/ptp_clock.h
+++ b/include/uapi/linux/ptp_clock.h
@@ -38,8 +38,8 @@
 /*
  * Bits of the ptp_perout_request.flags field:
  */
-#define PTP_PEROUT_VALID_FLAGS (0)
-
+#define PTP_PEROUT_ONE_SHOT (1<<0)
+#define PTP_PEROUT_VALID_FLAGS	(PTP_PEROUT_ONE_SHOT)
 /*
  * struct ptp_clock_time - represents a time value
  *
@@ -77,7 +77,7 @@ struct ptp_perout_request {
 	struct ptp_clock_time start;  /* Absolute start time. */
 	struct ptp_clock_time period; /* Desired period, zero means disable. */
 	unsigned int index;           /* Which channel to configure. */
-	unsigned int flags;           /* Reserved for future use. */
+	unsigned int flags;
 	unsigned int rsv[4];          /* Reserved for future use. */
 };