ASSUMESTDTYPES
diff --git a/skeletons/asn_system.h b/skeletons/asn_system.h
index 39a1f9e..0a9b092 100644
--- a/skeletons/asn_system.h
+++ b/skeletons/asn_system.h
@@ -37,6 +37,7 @@
#ifndef __cplusplus
#define inline __inline
#endif
+#ifndef ASSUMESTDTYPES /* Standard types have been defined elsewhere */
#define ssize_t SSIZE_T
typedef char int8_t;
typedef short int16_t;
@@ -44,6 +45,7 @@
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned int uint32_t;
+#endif /* ASSUMESTDTYPES */
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <float.h>