diff --git a/configure.ac b/configure.ac
index 0915a5c..8ba501c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -79,7 +79,6 @@ AC_CHECK_FUNCS(mmap getpagesize)
 AC_CHECK_FUNCS(getc_unlocked getchar_unlocked fgetc_unlocked fread_unlocked fgets_unlocked)
 AC_CHECK_FUNCS(__getdelim __srefill __filbuf __srget __uflow)
 AC_CHECK_FUNCS(open64 lseek64 mmap64 fopen64 freopen64 ftello64 fseeko64 fsetpos64)
-AC_CHECK_FUNCS(__open64 __lseek64 __fopen64 __freopen64 __ftello64 __fseeko64 __fsetpos64)
 AC_CHECK_FUNCS(__fgets_chk __fgets_unlocked_chk __fread_chk __fread_unlocked_chk __read_chk __recv_chk __recvfrom_chk)
 AC_CHECK_FUNCS(CreateFileA CreateFileW ReOpenFile ReadFile CloseHandle)
 AC_CHECK_FUNCS(AllocConsole AttachConsole SetConsoleMode WriteConsoleOutputA WriteConsoleOutputW)