diff --git a/mingw-w64-headers/crt/sec_api/string_s.h b/mingw-w64-headers/crt/sec_api/string_s.h
index 34d1c99..40eebf6 100644
--- a/mingw-w64-headers/crt/sec_api/string_s.h
+++ b/mingw-w64-headers/crt/sec_api/string_s.h
@@ -60,6 +60,9 @@
   _CRTIMP errno_t __cdecl _wcsset_s_l(wchar_t *_Str,size_t _SizeInChars,unsigned int _Val,_locale_t _Locale);
   _CRTIMP errno_t __cdecl _wcsnset_s_l(wchar_t *_Str,size_t _SizeInChars,unsigned int _Val, size_t _Count,_locale_t _Locale);
 
+  extern inline size_t __cdecl wcsnlen_s(const wchar_t * _src, size_t _count) {
+    return _src ? wcsnlen(_src, _count) : 0;
+  }
 #endif
 
 #ifndef _MEMORY_S_DEFINED
diff --git a/mingw-w64-headers/crt/sec_api/wchar_s.h b/mingw-w64-headers/crt/sec_api/wchar_s.h
index fc8fc4d..611f934 100644
--- a/mingw-w64-headers/crt/sec_api/wchar_s.h
+++ b/mingw-w64-headers/crt/sec_api/wchar_s.h
@@ -130,6 +130,9 @@
   _CRTIMP errno_t __cdecl _wcsset_s_l(wchar_t *_Str,size_t _SizeInChars,unsigned int _Val,_locale_t _Locale);
   _CRTIMP errno_t __cdecl _wcsnset_s_l(wchar_t *_Str,size_t _SizeInChars,unsigned int _Val, size_t _Count,_locale_t _Locale);
 
+  extern inline size_t __cdecl wcsnlen_s(const wchar_t * _src, size_t _count) {
+    return _src ? wcsnlen(_src, _count) : 0;
+  }
 #endif
 
 #ifndef _WTIME_S_DEFINED