diff --git a/gtests/net/packetdrill/run_packet.c b/gtests/net/packetdrill/run_packet.c
index cbb0b0e5a66e421a91a14950369afba7e780485e..2b6ec86a3b12aed4387235ce106671a65c38f05b 100644
--- a/gtests/net/packetdrill/run_packet.c
+++ b/gtests/net/packetdrill/run_packet.c
@@ -636,7 +636,7 @@ static int map_inbound_sctp_packet(
 			nr_gap_blocks = ntohs(sack->nr_gap_blocks);
 			nr_dup_tsns = ntohs(sack->nr_dup_tsns);
 
-			if (ntohs(sack->length) == (sizeof(struct sctp_sack_chunk)+(sizeof(union sctp_sack_block()))*nr_gap_blocks+(sizeof(union sctp_sack_block))*nr_dup_tsns)) {
+			if (ntohs(sack->length) == (sizeof(struct sctp_sack_chunk)+(sizeof(union sctp_sack_block))*nr_gap_blocks+(sizeof(union sctp_sack_block))*nr_dup_tsns)) {
 				for (i = 0; i < nr_dup_tsns; i++) {
 					sack->block[i + nr_gap_blocks].tsn = htonl(ntohl(sack->block[i + nr_gap_blocks].tsn) + local_diff);
 				}