diff --git a/net/sock.h b/net/sock.h
index 72a5a4b..9b79407 100644
--- a/net/sock.h
+++ b/net/sock.h
@@ -22,6 +22,8 @@
 #ifndef __SOCK_H
 #define __SOCK_H
 
+#include <unistd.h>
+
 #ifdef _WIN32
 #include <winsock2.h>
 #endif