diff --git a/beautiful-racket/br/demo/basic/expander.rkt b/beautiful-racket/br/demo/basic/expander.rkt
index ce6c759..86ea89d 100644
--- a/beautiful-racket/br/demo/basic/expander.rkt
+++ b/beautiful-racket/br/demo/basic/expander.rkt
@@ -103,6 +103,10 @@
 (define (basic:and . args) (cond->int (andmap true? args)))
 (define (basic:or . args) (cond->int (ormap true? args)))
 
+(define-cases #'expr-list
+  [#'(_ _EXPR) #'_EXPR]
+  [#'(_ _EXPR "," _EXPR-LIST) #'(_EXPR _EXPR-LIST)])
+
 (define-cases #'expr
   [#'(_ _COMP-EXPR "AND" _SUBEXPR) #'(basic:and _COMP-EXPR _SUBEXPR)]
   [#'(_ _COMP-EXPR "OR" _SUBEXPR) #'(basic:or _COMP-EXPR _SUBEXPR)]
@@ -121,9 +125,9 @@
   [#'(_ _TERM) #'_TERM])
 
 (define-cases #'product
-  [#'(_ _FACTOR "*" _PRODUCT) #'(* _FACTOR _PRODUCT)]
-  [#'(_ _FACTOR "/" _PRODUCT) #'(/ _FACTOR _PRODUCT)]
-  [#'(_ _FACTOR) #'_FACTOR])
+  [#'(_ _value "*" _product) #'(* _value _product)]
+  [#'(_ _value "/" _product) #'(/ _value _product)]
+  [#'(_ _value) #'_value])
 
 (define print-list list)
 
diff --git a/beautiful-racket/br/demo/basic/parser.rkt b/beautiful-racket/br/demo/basic/parser.rkt
index 0cddd8f..a4e148d 100644
--- a/beautiful-racket/br/demo/basic/parser.rkt
+++ b/beautiful-racket/br/demo/basic/parser.rkt
@@ -26,7 +26,9 @@ sum : product [("+" | "-") sum]
 
 product : value [("*" | "/") product]
 
-value : ID ["(" expr* ")"]
+expr-list : expr ["," expr-list]*
+
+value : ID ["(" expr-list ")"]
 | "(" expr ")"
 | STRING
 | NUMBER