diff --git a/src/scan.c b/src/scan.c
index 9a67731..fa3ec2a 100644
--- a/src/scan.c
+++ b/src/scan.c
@@ -19,33 +19,22 @@ static void dispatch_callback(u_char *user, const struct pcap_pkthdr *h,
 	const struct scan *data = (struct scan *)user;
 	const struct iphdr *iphdr =
 	    (struct iphdr *)(bytes + sizeof(struct ether_header));
+	const void *packet = bytes + sizeof(struct ether_header) + sizeof(struct iphdr);
 
 	if (iphdr->protocol == IPPROTO_TCP &&
 	    h->caplen >= sizeof(struct ether_header) + sizeof(struct iphdr) +
 	                     sizeof(struct tcphdr)) {
-		tcp_response(
-		    (const struct tcphdr *)(bytes +
-		                            sizeof(struct ether_header) +
-		                            sizeof(struct iphdr)),
-		    data);
+		tcp_response(packet, data);
 	}
 	if (iphdr->protocol == IPPROTO_UDP &&
 	    h->caplen >= sizeof(struct ether_header) + sizeof(struct iphdr) +
 	                     sizeof(struct udphdr)) {
-		udp_response(
-		    (const struct udphdr *)(bytes +
-		                            sizeof(struct ether_header) +
-		                            sizeof(struct iphdr)),
-		    data);
+		udp_response(packet, data);
 	}
 	if (iphdr->protocol == IPPROTO_ICMP &&
 	    h->caplen >= sizeof(struct ether_header) + sizeof(struct iphdr) +
 	                     sizeof(struct icmphdr)) {
-		icmp_response(
-		    (const struct icmphdr *)(bytes +
-		                             sizeof(struct ether_header) +
-		                             sizeof(struct iphdr)),
-		    data);
+		icmp_response(packet, data);
 	}
 }