diff --git a/c/src/win32.c b/c/src/win32.c
index 4014cd2..c92afbb 100644
--- a/c/src/win32.c
+++ b/c/src/win32.c
@@ -11,6 +11,10 @@
 #pragma comment(lib, "User32.lib")
 #pragma comment(lib, "OleAut32.lib")
 
+#ifndef WC_ERR_INVALID_CHARS
+#define WC_ERR_INVALID_CHARS 0x80
+#endif
+
 
 
 char* bw_win32_unhandledHresultMessage( bw_ErrCode code, const void* data );