diff --git a/extra/peg/pl0/pl0.factor b/extra/peg/pl0/pl0.factor
index b30f6bfe70..34973e6a52 100644
--- a/extra/peg/pl0/pl0.factor
+++ b/extra/peg/pl0/pl0.factor
@@ -1,18 +1,10 @@
 ! Copyright (C) 2007 Chris Double.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel arrays strings math.parser sequences
-peg peg.ebnf peg.parsers memoize namespaces ;
+peg peg.ebnf peg.parsers memoize namespaces math ;
 IN: peg.pl0
 
 #! Grammar for PL/0 based on http://en.wikipedia.org/wiki/PL/0
-MEMO: ident ( -- parser )
-  [
-    CHAR: a CHAR: z range ,
-    CHAR: A CHAR: Z range ,
-  ] choice* repeat1 [ >string ] action ;
-
-MEMO: number ( -- parser )
-  CHAR: 0 CHAR: 9 range repeat1 [ string>number ] action ;
 
 <EBNF
 program = block "." 
@@ -28,4 +20,7 @@ condition = "ODD" expression |
 expression = ("+" | "-")? term (("+" | "-") term )* 
 term = factor (("*" | "/") factor )* 
 factor = ident | number | "(" expression ")"
+ident = (([a-zA-Z])+) [[ >string ]]
+digit = ([0-9]) [[ digit> ]]
+number = ((digit)+) [[ unclip [ swap 10 * + ] reduce ]]
 EBNF>