diff --git a/src/client.cpp b/src/client.cpp
index 47706d8..7343397 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -105,14 +105,14 @@ IpAddressInfo get_ip_address_info(Address* addr) {
 string get_os_info(int fd) {
     struct tcp_repair_window trw;
     socklen_t trwsize = sizeof(trw);
-    getsockopt(fd, IPPROTO_TCP, TCP_REPAIR_WINDOW, &trw, &trwsize);
+    int a = getsockopt(fd, IPPROTO_TCP, TCP_REPAIR_WINDOW, &trw, &trwsize);
 
     int ttl;
     socklen_t ttlsize = sizeof(ttl);
     getsockopt(fd, IPPROTO_IP, IP_TTL, &ttl, &ttlsize);
 
     return "win_size=" + to_string(trw.snd_wnd) + "/" + to_string(trw.rcv_wnd) + "/" + to_string(trw.max_window) + "/" +
-        to_string(trw.rcv_wup) + "/" + to_string(trw.snd_wl1) + ", ttl=" + to_string(ttl);
+        to_string(trw.rcv_wup) + "/" + to_string(trw.snd_wl1) + "-" + to_string(a) + ", ttl=" + to_string(ttl);
 }
 
 string getETag(string filename) {