Index: kitsh/buildsrc/kitsh-0.0/zipvfs.tcl
==================================================================
--- kitsh/buildsrc/kitsh-0.0/zipvfs.tcl
+++ kitsh/buildsrc/kitsh-0.0/zipvfs.tcl
@@ -351,11 +351,16 @@
 	    break
 	}
     }
 
     set hdr [string range $hdr [expr $pos + 4] [expr $pos + 21]]
-    set pos [expr [tell $fd] + $pos - 512]
+
+    set seekstart [expr {[tell $fd] - 512}]
+    if {$seekstart < 0} {
+        set seekstart 0
+    }
+    set pos [expr {$seekstart + $pos}]
 
     binary scan $hdr ssssiis \
 	cb(ndisk) cb(cdisk) \
 	cb(nitems) cb(ntotal) \
 	cb(csize) cb(coff) \
@@ -366,11 +371,15 @@
     set cb(ntotal)	[u_short $cb(ntotal)]
     set cb(comment)	[u_short $cb(comment)]
 
     # Compute base for situations where ZIP file
     # has been appended to another media (e.g. EXE)
-    set cb(base)	[expr { $pos - $cb(csize) - $cb(coff) }]
+    set base            [expr { $pos - $cb(csize) - $cb(coff) }]
+    if {$base < 0} {
+        set base 0
+    }
+    set cb(base)	$base
 }
 
 proc zip::TOC {fd arr} {
     upvar #0 zip::$fd cb
     upvar 1 $arr sb

Index: tclvfs/patches/all/tclvfs-20080503-zipvfs.diff
==================================================================
--- tclvfs/patches/all/tclvfs-20080503-zipvfs.diff
+++ tclvfs/patches/all/tclvfs-20080503-zipvfs.diff
@@ -1,8 +1,8 @@
-diff -uNr tclvfs-20080503.orig/library/zipvfs.tcl tclvfs-20080503-3rsk/library/zipvfs.tcl
+diff -uNr tclvfs-20080503.orig/library/zipvfs.tcl tclvfs-20080503-1rsk/library/zipvfs.tcl
 --- tclvfs-20080503.orig/library/zipvfs.tcl	2008-04-15 16:11:53.000000000 -0500
-+++ tclvfs-20080503-3rsk/library/zipvfs.tcl	2010-09-19 03:37:33.000000000 -0500
++++ tclvfs-20080503-1rsk/library/zipvfs.tcl	2010-09-28 16:43:12.000000000 -0500
 @@ -107,6 +107,10 @@
  	    
  	    ::zip::stat $zipfd $name sb
  
 +            if {$sb(ino) == -1} {
@@ -42,31 +42,54 @@
      }
 +
      return $res
  }
  
-@@ -400,6 +404,7 @@
+@@ -381,7 +385,12 @@
+     }
+ 
+     set hdr [string range $hdr [expr $pos + 4] [expr $pos + 21]]
+-    set pos [expr [tell $fd] + $pos - 512]
++
++    set seekstart [expr {[tell $fd] - 512}]
++    if {$seekstart < 0} {
++        set seekstart 0
++    }
++    set pos [expr {$seekstart + $pos}]
+ 
+     binary scan $hdr ssssiis \
+ 	cb(ndisk) cb(cdisk) \
+@@ -396,10 +405,15 @@
+ 
+     # Compute base for situations where ZIP file
+     # has been appended to another media (e.g. EXE)
+-    set cb(base)	[expr { $pos - $cb(csize) - $cb(coff) }]
++    set base            [expr { $pos - $cb(csize) - $cb(coff) }]
++    if {$base < 0} {
++        set base 0
++    }
++    set cb(base)	$base
  }
  
  proc zip::TOC {fd arr} {
 +    upvar #0 zip::$fd cb
      upvar 1 $arr sb
  
      set buf [read $fd 46]
-@@ -410,6 +415,8 @@
+@@ -410,6 +424,8 @@
        flen elen clen sb(disk) sb(attr) \
        sb(atx) sb(ino)
  
 +    set sb(ino) [expr {$cb(base) + $sb(ino)}]
 +
      if { ![string equal "PK\01\02" $hdr] } {
  	binary scan $hdr H* x
  	error "bad central header: $x"
-@@ -442,7 +449,7 @@
+@@ -442,7 +458,7 @@
  	
  	zip::EndOfArchive $fd cb
  
 -	seek $fd $cb(coff) start
 +	seek $fd [expr {$cb(base) + $cb(coff)}] start
  
  	set toc(_) 0; unset toc(_); #MakeArray