This file is part of MXE. See index.html for further information. Some functions in netioapi.h were only added in Windows Vista. This patch removes function definitions for if_nametoindex and if_indextoname on older API versions, so they don't conflict with replacement implementations in libraries (e.g. glib). This is fixed on the 4.x branch of mingw-w64. diff -Naur mingw-w64-v3.3.0.orig/mingw-w64-headers/include/netioapi.h mingw-w64-v3.3.0/mingw-w64-headers/include/netioapi.h --- mingw-w64-v3.3.0.orig/mingw-w64-headers/include/netioapi.h 2015-01-17 00:07:51.030935703 +0100 +++ mingw-w64-v3.3.0/mingw-w64-headers/include/netioapi.h 2015-01-17 01:09:47.546591536 +0100 @@ -311,6 +311,7 @@ PNET_LUID InterfaceLuid ); +#if (_WIN32_WINNT >= 0x0600) PCHAR WINAPI if_indextoname( NET_IFINDEX InterfaceIndex, PCHAR InterfaceName @@ -319,6 +320,7 @@ NET_IFINDEX WINAPI if_nametoindex( PCSTR InterfaceName ); +#endif NETIO_STATUS WINAPI ConvertInterfaceGuidToLuid( const GUID *InterfaceGuid,