diff --git a/chapter9/happy/Parser.y b/chapter9/happy/Parser.y
index da837ca..8eae07a 100644
--- a/chapter9/happy/Parser.y
+++ b/chapter9/happy/Parser.y
@@ -64,7 +64,7 @@ Atom : '(' Expr ')'                { $2 }
      | NUM                         { Lit (LInt $1) }
      | VAR                         { Var $1 }
      | true                        { Lit (LBool True) }
-     | false                       { Lit (LBool True) }
+     | false                       { Lit (LBool False) }
 
 {