diff --git a/matlab/@ucf/ucf.m b/matlab/@ucf/ucf.m
index 7b9cdb4..2d1da1f 100644
--- a/matlab/@ucf/ucf.m
+++ b/matlab/@ucf/ucf.m
@@ -120,7 +120,7 @@ classdef ucf < handle
       if obj.fileID<0
         error('Unable to open file: %s',obj.File);
       end
-      obj.fileBeg = ftell(fid);
+      obj.fileBeg = ftell(obj.fileID);
       fseek(obj.fileID,0,'eof');
       obj.fileEnd = ftell(obj.fileID);
       fseek(obj.fileID,0,'bof');