diff --git a/test/HttpClient.h b/test/HttpClient.h
index 51145f8..e0c6ccb 100644
--- a/test/HttpClient.h
+++ b/test/HttpClient.h
@@ -18,6 +18,7 @@
     #include <unistd.h> /* close */
     #include <netdb.h> /* gethostbyname */
     #define SOCKET_ERROR -1
+    #define INVALID_SOCKET -1
     #ifndef closesocket
         #define closesocket(s) close(s)
     #endif