Index: tiff-4.6.0/libtiff/tiffiop.h
===================================================================
--- tiff-4.6.0.orig/libtiff/tiffiop.h
+++ tiff-4.6.0/libtiff/tiffiop.h
@@ -256,7 +256,7 @@ struct TIFFOpenOptions
 #define TIFFWriteFile(tif, buf, size)                                          \
     ((*(tif)->tif_writeproc)((tif)->tif_clientdata, (buf), (size)))
 #define TIFFSeekFile(tif, off, whence)                                         \
-    ((*(tif)->tif_seekproc)((tif)->tif_clientdata, (off), (whence)))
+  	((tif)->tif_seekproc?((*(tif)->tif_seekproc)((tif)->tif_clientdata,(toff_t)(off),whence)):0)
 #define TIFFCloseFile(tif) ((*(tif)->tif_closeproc)((tif)->tif_clientdata))
 #define TIFFGetFileSize(tif) ((*(tif)->tif_sizeproc)((tif)->tif_clientdata))
 #define TIFFMapFileContents(tif, paddr, psize)                                 \