diff --git a/include/osg/Types b/include/osg/Types
index 8c749e705..568561e20 100644
--- a/include/osg/Types
+++ b/include/osg/Types
@@ -15,13 +15,13 @@
 #define __OSG_TYPES
 
 #if defined(_MSC_VER) && _MSC_VER < 1600
-typedef __int8 int8_t;
-typedef unsigned __int8 uint8_t;
-typedef __int16 int16_t;
+typedef signed __int8    int8_t;
+typedef unsigned __int8  uint8_t;
+typedef signed __int16   int16_t;
 typedef unsigned __int16 uint16_t;
-typedef __int32 int32_t;
+typedef signed __int32   int32_t;
 typedef unsigned __int32 uint32_t;
-typedef __int64 int64_t;
+typedef signed __int64   int64_t;
 typedef unsigned __int64 uint64_t;
 #else
 #include <stdint.h>