diff --git a/extra/peg/peg.factor b/extra/peg/peg.factor
index 247d52a19c..39aacd974e 100644
--- a/extra/peg/peg.factor
+++ b/extra/peg/peg.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2007 Chris Double.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel sequences strings namespaces math assocs shuffle 
-       vectors arrays combinators.lib ;
+       vectors arrays combinators.lib memoize ;
 IN: peg
 
 TUPLE: parse-result remaining ast ;
@@ -217,13 +217,13 @@ M: delay-parser (parse) ( state parser -- result )
 
 PRIVATE>
 
-: token ( string -- parser )
+MEMO: token ( string -- parser )
   token-parser construct-boa init-parser ;      
 
 : satisfy ( quot -- parser )
   satisfy-parser construct-boa init-parser ;
 
-: range ( min max -- parser )
+MEMO: range ( min max -- parser )
   range-parser construct-boa init-parser ;
 
 : seq ( seq -- parser )
@@ -232,32 +232,32 @@ PRIVATE>
 : choice ( seq -- parser )
   choice-parser construct-boa init-parser ;
 
-: repeat0 ( parser -- parser )
+MEMO: repeat0 ( parser -- parser )
   repeat0-parser construct-boa init-parser ;
 
-: repeat1 ( parser -- parser )
+MEMO: repeat1 ( parser -- parser )
   repeat1-parser construct-boa init-parser ;
 
-: optional ( parser -- parser )
+MEMO: optional ( parser -- parser )
   optional-parser construct-boa init-parser ;
 
-: ensure ( parser -- parser )
+MEMO: ensure ( parser -- parser )
   ensure-parser construct-boa init-parser ;
 
-: ensure-not ( parser -- parser )
+MEMO: ensure-not ( parser -- parser )
   ensure-not-parser construct-boa init-parser ;
 
 : action ( parser quot -- parser )
   action-parser construct-boa init-parser ;
 
-: sp ( parser -- parser )
+MEMO: sp ( parser -- parser )
   sp-parser construct-boa init-parser ;
 
-: hide ( parser -- parser )
+MEMO: hide ( parser -- parser )
   [ drop ignore ] action ;
 
-: delay ( parser -- parser )
+MEMO: delay ( parser -- parser )
   delay-parser construct-boa init-parser ;
 
-: list-of ( items separator -- parser )
+MEMO: list-of ( items separator -- parser )
   hide over 2array seq repeat0 [ concat ] action 2array seq [ unclip 1vector swap first append ] action ;