diff --git a/slides.md b/slides.md
index fb5ff74..20fe91a 100644
--- a/slides.md
+++ b/slides.md
@@ -145,6 +145,20 @@
 
 ---
 
+# Records: Constructor canónico
+
+```java
+public record Movie(String title, List<String> cast) {
+    public Movie {
+        cast = List.copyOf(cast);
+    }
+}
+```
+
+* copia defensiva para evitar modificar el contenido del record.
+
+---
+
 # Sealed classes and interfaces :closed_lock_with_key:
 
 ```java
@@ -287,7 +301,7 @@
 * Productos y sumas de tipos.
     `a + b` `a * b`
 * Cardinalidad.
-* Se les llama algebraicos porque tienen propiedades algebraicas.
+* Tienen propiedades algebraicas.
 
 ---
 
diff --git a/snippets/Movie.java b/snippets/Movie.java
index 817989e..caeb257 100644
--- a/snippets/Movie.java
+++ b/snippets/Movie.java
@@ -1,8 +1,11 @@
-public record Movie(String title, int year, int duration) {
+import java.util.List;
+
+public record Movie(String title, int year, int duration, List<String> cast) {
 
     public Movie {
         if (title == null || title.isEmpty()) {
             throw new IllegalArgumentException();
         }
+        cast = List.copyOf(cast);
     }
 }