diff --git a/src/hb-private.hh b/src/hb-private.hh
index 783e73cba..f5bf6c603 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -127,6 +127,7 @@
 #    define _WIN32_WINNT 0x0600
 #  endif
 #  define WIN32_LEAN_AND_MEAN
+#  define STRICT
 #endif