diff --git a/src/connection.c b/src/connection.c
index e716e80..8d2fb77 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -763,9 +763,9 @@
 
 		hdr_ip4 = (struct ip *)line;
 
-		if (trash.len < ntohs(hdr_ip4->ip_len)) {
+		if (trash.len < (ntohs(hdr_ip4->ip_len) + 20)) {
 			/* Fail if buffer length is not large enough to contain
-			 * IPv4 header */
+			 * IPv4 header, TCP header */
 			goto missing;
 		}
 		else if (hdr_ip4->ip_p != IPPROTO_TCP) {
@@ -773,11 +773,6 @@
 			conn->err_code = CO_ER_CIP_BAD_PROTO;
 			goto fail;
 		}
-		else if (trash.len < (20 + ntohs(hdr_ip4->ip_len))) {
-			/* Fail if buffer length is not large enough to contain
-			 * IPv4 header, TCP header */
-			goto missing;
-		}
 
 		hdr_tcp = (struct my_tcphdr *)(line + (hdr_ip4->ip_hl * 4));
 
@@ -798,9 +793,9 @@
 
 		hdr_ip6 = (struct ip6_hdr *)line;
 
-		if (trash.len < 40) {
+		if (trash.len < 60) {
 			/* Fail if buffer length is not large enough to contain
-			 * IPv6 header */
+			 * IPv6 header, TCP header */
 			goto missing;
 		}
 		else if (hdr_ip6->ip6_nxt != IPPROTO_TCP) {
@@ -808,11 +803,6 @@
 			conn->err_code = CO_ER_CIP_BAD_PROTO;
 			goto fail;
 		}
-		else if (trash.len < 60) {
-			/* Fail if buffer length is not large enough to contain
-			 * IPv6 header, TCP header */
-			goto missing;
-		}
 
 		hdr_tcp = (struct my_tcphdr *)(line + sizeof(struct ip6_hdr));