diff --git a/src/nfd_win.cpp b/src/nfd_win.cpp
index 949da2b..d01dc60 100644
--- a/src/nfd_win.cpp
+++ b/src/nfd_win.cpp
@@ -8,7 +8,12 @@
 #ifdef __MINGW32__
 // Explicitly setting NTDDI version, this is necessary for the MinGW compiler
 #define NTDDI_VERSION NTDDI_VISTA
+
+#ifdef _WIN32_WINNT
+#undef _WIN32_WINNT   // Prevent a warning about overwriting an existing define by first undefining it
+#endif
 #define _WIN32_WINNT _WIN32_WINNT_VISTA
+
 #endif
 
 #define _CRTDBG_MAP_ALLOC