gistfile1.diff

diff --git a/lib/strscan.rb b/lib/strscan.rb
index 3908bfb..b2ac46c 100644
--- a/lib/strscan.rb
+++ b/lib/strscan.rb
@@ -161,7 +161,7 @@ class StringScanner
   end
 
   def rest
-    @string[pos..-1]
+    @string.substring(@pos, rest_size)
   end
 
   def rest?
@@ -169,7 +169,7 @@ class StringScanner
   end
 
   def rest_size
-    rest.size
+    @string.size - @pos
   end
 
   def restsize