diff --git a/client.c b/client.c
index 22a2d5e..3c7d773 100644
--- a/client.c
+++ b/client.c
@@ -84,7 +84,7 @@ int main(int argc,char *argv[]) {   //usage: ./client host port
                         else puts("Send file error.");
                     #else
                         send(sockfd, &file_size, sizeof(uint32_t), 0);
-                        if(!sendfile(sockfd, fileno(fp), &len, file_size)) puts("Send file success.");
+                        if(!sendfile(sockfd, fileno(fp), &len, htonl(file_size))) puts("Send file success.");
                         else puts("Send file error.");
                     #endif
                     fclose(fp);
diff --git a/server.c b/server.c
index d7e5366..6c8fe85 100644
--- a/server.c
+++ b/server.c
@@ -126,6 +126,7 @@ int sendAll(char* file_path, THREADTIMER *timer) {
         timer->fp = fp;
         timer->is_open = 1;
         uint32_t file_size = (uint32_t)fileSize(file_path);
+        printf("Get file size: %u bytes.\n", file_size);
         off_t len;
         #if __APPLE__
             struct iovec headers;
@@ -136,7 +137,7 @@ int sendAll(char* file_path, THREADTIMER *timer) {
             sendfile(fileno(fp), timer->accept_fd, 0, &len, &hdtr, 0);
         #else
             send(timer->accept_fd, &file_size, sizeof(uint32_t), 0);
-            sendfile(timer->accept_fd, fileno(fp), &len, file_size);
+            sendfile(timer->accept_fd, fileno(fp), &len, htonl(file_size));
         #endif
         printf("Send %lld bytes.\n", len);
         closeFile(fp);