Index: src/shorten.c
--- src/shorten.c.orig
+++ src/shorten.c
@@ -334,7 +334,7 @@ BOOL FileHasSeekInfoAppended(FILE *filei,ulong *seekta
 
   if(0==memcmp(SeekTrailerSignature,SeekTrailer.data+4,8)) {
     if (seektable_version) {
-      fseek(filei,-uchar_to_ulong_le(SeekTrailer.data),SEEK_END);
+      fseek(filei,-(long)uchar_to_ulong_le(SeekTrailer.data),SEEK_END);
       fread(SeekHeader.data,1,SEEK_HEADER_SIZE,filei);
 
       if (0==memcmp(SeekHeaderSignature,SeekHeader.data,4)) {
