diff --git a/test/widechars.h b/test/widechars.h
index e7897ba..2578a92 100644
--- a/test/widechars.h
+++ b/test/widechars.h
@@ -1,5 +1,6 @@
 /****************************************************************************
- * Copyright (c) 2012 Free Software Foundation, Inc.                        *
+ * Copyright 2018,2020 Thomas E. Dickey                                     *
+ * Copyright 2012 Free Software Foundation, Inc.                            *
  *                                                                          *
  * Permission is hereby granted, free of charge, to any person obtaining a  *
  * copy of this software and associated documentation files (the            *
@@ -33,7 +34,7 @@
 
 #if USE_WIDEC_SUPPORT
 
-#if defined(__MINGW32__)
+#if defined(_NC_WINDOWS) && !defined(_MSC_VER) && !defined(EXP_WIN32_DRIVER)
 /*
  * MinGW has wide-character functions, but they do not work correctly.
  */
@@ -45,7 +46,7 @@
 extern int __MINGW_NOTHROW _nc_mblen(const char *, size_t);
 #define mblen(s,n) _nc_mblen(s, n)
 
-#endif /* __MINGW32__ */
+#endif /* _WIN32||_WIN64 */
 
 #if HAVE_MBTOWC && HAVE_MBLEN
 #define reset_mbytes(state) IGNORE_RC(mblen(NULL, 0)), IGNORE_RC(mbtowc(NULL, NULL, 0))