diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 148e73d..e356b8d 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2927,7 +2927,7 @@
 		  sizeof(struct ipv6hdr) - sizeof(struct udphdr) -
 		  pkt_dev->pkt_overhead;
 
-	if (datalen < sizeof(struct pktgen_hdr)) {
+	if (datalen < 0 || datalen < sizeof(struct pktgen_hdr)) {
 		datalen = sizeof(struct pktgen_hdr);
 		net_info_ratelimited("increased datalen to %d\n", datalen);
 	}