diff --git a/src/afd.h b/src/afd.h
index f56791b..0b7e27e 100644
--- a/src/afd.h
+++ b/src/afd.h
@@ -1,9 +1,8 @@
 #ifndef EPOLL_AFD_H_
 #define EPOLL_AFD_H_
 
-#include <Windows.h>
-
 #include "nt.h"
+#include "win.h"
 
 #ifndef SIO_BASE_HANDLE
 #define SIO_BASE_HANDLE 0x48000022
diff --git a/src/epoll.c b/src/epoll.c
index 777d4b3..9505615 100644
--- a/src/epoll.c
+++ b/src/epoll.c
@@ -1,7 +1,3 @@
-#define WIN32_LEAN_AND_MEAN
-#include <WinSock2.h>
-#include <Windows.h>
-
 #include <assert.h>
 #include <malloc.h>
 #include <stdint.h>
@@ -11,6 +7,7 @@
 #include "epoll.h"
 #include "error.h"
 #include "tree.h"
+#include "win.h"
 
 #ifndef _SSIZE_T_DEFINED
 #define SSIZE_T_DEFINED
diff --git a/src/error.c b/src/error.c
index 9a32c17..ef7ecee 100644
--- a/src/error.c
+++ b/src/error.c
@@ -1,10 +1,7 @@
-#define WIN32_LEAN_AND_MEAN
-#include <WinSock2.h>
-#include <Windows.h>
-
 #include <errno.h>
 
 #include "error-map.h"
+#include "win.h"
 
 #pragma warning(push)
 #pragma warning(disable : 4127) /* "conditional expression is constant" */
diff --git a/src/nt.h b/src/nt.h
index 69052ca..3204301 100644
--- a/src/nt.h
+++ b/src/nt.h
@@ -1,7 +1,7 @@
 #ifndef EPOLL_NT_H_
 #define EPOLL_NT_H_
 
-#include <Windows.h>
+#include "win.h"
 
 #ifndef _NTDEF_
 typedef LONG NTSTATUS;
diff --git a/src/win.h b/src/win.h
new file mode 100644
index 0000000..995f5e9
--- /dev/null
+++ b/src/win.h
@@ -0,0 +1,12 @@
+#ifndef EPOLL_WIN_H_
+#define EPOLL_WIN_H_
+
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+
+#include <WS2tcpip.h>
+#include <WinSock2.h>
+#include <Windows.h>
+
+#endif
diff --git a/test/test-udp-pings.c b/test/test-udp-pings.c
index 3109ba7..7136e58 100644
--- a/test/test-udp-pings.c
+++ b/test/test-udp-pings.c
@@ -1,10 +1,7 @@
-#include <WS2tcpip.h>
-#include <WinSock2.h>
-#include <Windows.h>
-
 #include <assert.h>
 #include <stdio.h>
 
+#include "win.h"
 #include "epoll.h"
 
 static const char PING[] = "PING";