Index: pinboard.lua
==================================================================
--- pinboard.lua
+++ pinboard.lua
@@ -101,12 +101,12 @@
 function hx (c)
     return string.char((c >= 10 and (c - 10) + string.byte ('A')) or c + string.byte ('0'))
 end
 
 function char2hex (c)
-    return '%'..hx ((string.byte (c) / 16)-1)..hx (math.mod(string.byte (c), 16))
+    return '%'..hx (math.floor(string.byte (c) / 16))..hx (math.mod(string.byte (c), 16))
 end
 
 function escape (str)
     return string.gsub (str, "(%W)", char2hex)
 end
 --end stealing