diff --git a/examples/hello_world/aiken.lock b/examples/hello_world/aiken.lock
index 21fbf8f4..0f958098 100644
--- a/examples/hello_world/aiken.lock
+++ b/examples/hello_world/aiken.lock
@@ -13,4 +13,4 @@ requirements = []
 source = "github"
 
 [etags]
-"aiken-lang/stdlib@main" = [{ secs_since_epoch = 1716400776, nanos_since_epoch = 210636000 }, "6b89f2c51314a7bc2cc377d37c9eade9a4239086fe636ac6030c6979182f1247"]
+"aiken-lang/stdlib@main" = [{ secs_since_epoch = 1723580005, nanos_since_epoch = 641136000 }, "5e58899446492a704d0927a43299139856bef746e697b55895ba34206fa28452"]
diff --git a/examples/hello_world/validators/hello_world.ak b/examples/hello_world/validators/hello_world.ak
index 334aa194..ef3006c9 100644
--- a/examples/hello_world/validators/hello_world.ak
+++ b/examples/hello_world/validators/hello_world.ak
@@ -3,16 +3,16 @@ use aiken/list
 use aiken/transaction.{ScriptContext}
 use aiken/transaction/credential.{VerificationKey}
 
-type Datum {
+pub type Datum {
   owner: Hash<Blake2b_224, VerificationKey>,
 }
 
-type Redeemer {
+pub type Redeemer {
   msg: ByteArray,
 }
 
-validator {
-  fn spend(datum: Datum, redeemer: Redeemer, context: ScriptContext) -> Bool {
+validator hello_world {
+  spend(datum: Datum, redeemer: Redeemer, context: ScriptContext) -> Bool {
     let must_say_hello = redeemer.msg == "Hello, World!"
 
     let must_be_signed =
@@ -20,4 +20,8 @@ validator {
 
     must_say_hello && must_be_signed
   }
+
+  else(_ctx) {
+    fail
+  }
 }