diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c
index 679ae40916f7..e9cf4da3ed8a 100644
--- a/drivers/ptp/ptp_vclock.c
+++ b/drivers/ptp/ptp_vclock.c
@@ -326,6 +326,8 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index)
 	u64 ns;
 
 	ns = ktime_to_ns(*hwtstamp);
+	if (!ns)
+		return 0;
 
 	srcu_idx = srcu_read_lock(&vclock_srcu);
 
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 36a27a910595..56f6ab1855d3 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -496,7 +496,7 @@ int ptp_get_vclocks_index(int pclock_index, int **vclock_index);
  * @hwtstamp:     timestamp
  * @vclock_index: phc index of ptp vclock.
  *
- * Returns: converted timestamp, or 0 on error.
+ * Returns: converted timestamp, or 0 if @hwtstamp is zero or on error.
  */
 ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index);
 #else