Minor
diff --git a/src/hb-object-private.hh b/src/hb-object-private.hh
index 6a2f83d..2e4a385 100644
--- a/src/hb-object-private.hh
+++ b/src/hb-object-private.hh
@@ -63,7 +63,7 @@
 #define hb_atomic_int_set(AI, V)	g_atomic_int_set (&(AI), V)
 
 
-#elif _MSC_VER >= 1600
+#elif defined(_MSC_VER) && _MSC_VER >= 1600
 
 #include <intrin.h>