diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
index 4997963149f6..0bce3e0f1af0 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -521,6 +521,12 @@ static int igb_ptp_feature_enable_i210(struct ptp_clock_info *ptp,
 
 	switch (rq->type) {
 	case PTP_CLK_REQ_EXTTS:
+		/* Reject requests with unsupported flags */
+		if (rq->extts.flags & ~(PTP_ENABLE_FEATURE |
+					PTP_RISING_EDGE |
+					PTP_FALLING_EDGE))
+			return -EOPNOTSUPP;
+
 		if (on) {
 			pin = ptp_find_pin(igb->ptp_clock, PTP_PF_EXTTS,
 					   rq->extts.index);