diff --git a/libtiff/tif_unix.c b/libtiff/tif_unix.c
index 874f1feb..bea1ef78 100644
--- a/libtiff/tif_unix.c
+++ b/libtiff/tif_unix.c
@@ -162,7 +162,7 @@ _tiffMapProc(thandle_t fd, void** pbase, toff_t* psize)
 {
 	uint64 size64 = _tiffSizeProc(fd);
 	tmsize_t sizem = (tmsize_t)size64;
-	if ((uint64)sizem==size64) {
+	if (size64 && (uint64)sizem==size64) {
 		fd_as_handle_union_t fdh;
 		fdh.h = fd;
 		*pbase = (void*)
diff --git a/libtiff/tif_win32.c b/libtiff/tif_win32.c
index bf5fbfb3..b3110b23 100644
--- a/libtiff/tif_win32.c
+++ b/libtiff/tif_win32.c
@@ -156,8 +156,10 @@ static uint64
 _tiffSizeProc(thandle_t fd)
 {
 	ULARGE_INTEGER m;
-	m.LowPart=GetFileSize(fd,&m.HighPart);
-	return(m.QuadPart);
+	if (GetFileSizeEx(fd,&m))
+		return(m.QuadPart);
+	else
+		return(0);
 }
 
 static int
@@ -189,7 +191,7 @@ _tiffMapProc(thandle_t fd, void** pbase, toff_t* psize)
 
 	size = _tiffSizeProc(fd);
 	sizem = (tmsize_t)size;
-	if ((uint64)sizem!=size)
+	if (!size || (uint64)sizem!=size)
 		return (0);
 
 	/* By passing in 0 for the maximum file size, it specifies that we