diff --git a/src/rtl_tcp.c b/src/rtl_tcp.c
index 89b1fb9..84f5591 100644
--- a/src/rtl_tcp.c
+++ b/src/rtl_tcp.c
@@ -35,7 +35,7 @@
 #include <fcntl.h>
 #else
 #include <winsock2.h>
-#include <WS2tcpip.h>
+#include <ws2tcpip.h>
 #include "getopt/getopt.h"
 #endif