diff --git a/include/ifnow_now.h b/include/ifnow_now.h
index 8972300..f71eef5 100644
--- a/include/ifnow_now.h
+++ b/include/ifnow_now.h
@@ -12,7 +12,7 @@
 #define ERR_BIND_FAILED   (-3)
 #define ERR_FILTER_FAILED (-4)
 
-typedef int (*ifnow_now_receive_cb)(void *now_cfg, uint8_t *buf, uint32_t len);
+typedef int (*ifnow_now_receive_cb)(void *now_cfg, uint8_t *buf, ssize_t len);
 
 typedef struct {
   int fd_if_socket;
diff --git a/src/main.c b/src/main.c
index 7760aee..dbd8cc6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,5 +1,5 @@
 #include <stdio.h>
-#include <strings.h>
+#include <string.h>
 #include <stdint.h>
 
 #include "ifnow.h"
@@ -33,7 +33,7 @@ char *color_chart[] = {
 };
 uint8_t color_size = 15;
 
-int ifnow_now_receive_callback(void *cfg, uint8_t *buf, uint32_t len) {
+int ifnow_now_receive_callback(void *cfg, uint8_t *buf, ssize_t len) {
   ifnow_now_cfg_t *now_cfg = cfg;
 
   printf("NOW receive_count: %d\n", len);
diff --git a/src/now.c b/src/now.c
index b56d7d7..ecc5ce3 100644
--- a/src/now.c
+++ b/src/now.c
@@ -55,7 +55,7 @@ void *ifnow_thread_handle(void *arg) {
     receive_count = recv(now_cfg->fd_if_socket, receive_buffer, IFNOW_MAX_RECEIVE, MSG_TRUNC);
 
     if(receive_count > 0 && now_cfg->receive != NULL) {
-      now_cfg->receive(now_cfg, receive_buffer, receive_count);
+      now_cfg->receive(now_cfg, (uint8_t*)&receive_buffer, receive_count);
     }
   }
 }