diff --git a/dump.c b/dump.c
index 0fda4e7..27b75d1 100644
--- a/dump.c
+++ b/dump.c
@@ -162,7 +162,7 @@
 }
 
 /* print tcp header */
-void dump_tcp_generic(const struct tcphdr *tcp, const char *options, size_t options_size, uint32_t temp_checksum, const char *payload, size_t payload_size) {
+void dump_tcp_generic(const struct tcphdr *tcp, const uint8_t *options, size_t options_size, uint32_t temp_checksum, const uint8_t *payload, size_t payload_size) {
   uint16_t my_checksum;
 
   temp_checksum = ip_checksum_add(temp_checksum, tcp, sizeof(struct tcphdr));
@@ -205,7 +205,7 @@
 /* print ipv4/tcp header */
 void dump_tcp(const struct tcphdr *tcp, const struct iphdr *ip,
               const uint8_t *payload, size_t payload_size,
-              const char *options, size_t options_size) {
+              const uint8_t *options, size_t options_size) {
   uint32_t temp_checksum;
 
   temp_checksum = ipv4_pseudo_header_checksum(ip, sizeof(*tcp) + options_size + payload_size);
@@ -215,7 +215,7 @@
 /* print ipv6/tcp header */
 void dump_tcp6(const struct tcphdr *tcp, const struct ip6_hdr *ip6,
                const uint8_t *payload, size_t payload_size,
-               const char *options, size_t options_size) {
+               const uint8_t *options, size_t options_size) {
   uint32_t temp_checksum;
 
   temp_checksum = ipv6_pseudo_header_checksum(ip6, sizeof(*tcp) + options_size + payload_size, IPPROTO_TCP);