diff --git a/src/platforms/windows/windowsHandler.cpp b/src/platforms/windows/windowsHandler.cpp
index b0e2c760..88ba786c 100644
--- a/src/platforms/windows/windowsHandler.cpp
+++ b/src/platforms/windows/windowsHandler.cpp
@@ -31,11 +31,14 @@
 
 #include "vmime/platforms/windows/windowsCriticalSection.hpp"
 
+#include "vmime/utility/stringUtils.hpp"
+
 #include <time.h>
 #include <locale.h>
 #include <process.h>
 #include <windows.h>  // for winnls.h
 #include <winsock2.h> // for WSAStartup()
+#include <Ws2tcpip.h>
 #include <wincrypt.h>
 
 #if VMIME_HAVE_MLANG