Minor

src/hb-mutex-private.hh

diff --git a/src/hb-mutex-private.hh b/src/hb-mutex-private.hh
index 8efd27e..fc8ef49 100644
--- a/src/hb-mutex-private.hh
+++ b/src/hb-mutex-private.hh
@@ -44,6 +44,7 @@
 
 #elif !defined(HB_NO_MT) && defined(_MSC_VER) || defined(__MINGW32__)
 
+#define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 typedef CRITICAL_SECTION hb_mutex_impl_t;
 #define HB_MUTEX_IMPL_INIT	{ NULL, 0, 0, NULL, NULL, 0 }

src/hb-uniscribe.cc

diff --git a/src/hb-uniscribe.cc b/src/hb-uniscribe.cc
index 0ca87ec..79e62a0 100644
--- a/src/hb-uniscribe.cc
+++ b/src/hb-uniscribe.cc
@@ -25,6 +25,7 @@
  */
 
 #define _WIN32_WINNT 0x0600
+#define WIN32_LEAN_AND_MEAN
 
 #define HB_SHAPER uniscribe
 #include "hb-shaper-impl-private.hh"

src/hb-uniscribe.h

diff --git a/src/hb-uniscribe.h b/src/hb-uniscribe.h
index bb99f39..51887c8 100644
--- a/src/hb-uniscribe.h
+++ b/src/hb-uniscribe.h
@@ -29,7 +29,9 @@
 
 #include "hb.h"
 
+#ifndef _WIN32_WINNT
 #define _WIN32_WINNT 0x0600
+#endif
 #include <windows.h>
 
 HB_BEGIN_DECLS