diff --git a/extra/peg/expr/expr-tests.factor b/extra/peg/expr/expr-tests.factor
new file mode 100644
index 0000000000..0ed05765cd
--- /dev/null
+++ b/extra/peg/expr/expr-tests.factor
@@ -0,0 +1,25 @@
+! Copyright (C) 2007 Chris Double.
+! See http://factorcode.org/license.txt for BSD license.
+!
+USING: kernel tools.test peg.expr multiline sequences ;
+IN: temporary
+
+{ 5 } [
+  "2+3" eval-expr 
+] unit-test
+
+{ 6 } [
+  "2*3" eval-expr 
+] unit-test
+
+{ 14 } [
+  "2+3*4" eval-expr 
+] unit-test
+
+{ 17 } [
+  "2+3*4+3" eval-expr 
+] unit-test
+
+{ 23 } [
+  "2+3*(4+3)" eval-expr 
+] unit-test
diff --git a/extra/peg/expr/expr.factor b/extra/peg/expr/expr.factor
index ed13ac0e50..26ae76c0b0 100644
--- a/extra/peg/expr/expr.factor
+++ b/extra/peg/expr/expr.factor
@@ -16,9 +16,8 @@ divide   = ("/") [[ drop [ / ] ]]
 add      = ("+") [[ drop [ + ] ]]
 subtract = ("-") [[ drop [ - ] ]]
 
-digit    = "0" | "1" | "2" | "3" | "4" |
-           "5" | "6" | "7" | "8" | "9" 
-number   = ((digit)+) [[ concat string>number ]]
+digit    = ([0-9]) [[ digit> ]]
+number   = ((digit)+) [[ unclip [ swap 10 * + ] reduce ]]
 
 value    = number | ("(" expr ")") [[ second ]] 
 product = (value ((times | divide) value)*) [[ first2 operator-fold ]]