diff --git a/src/castable.h b/src/castable.h
index 5bb8fdb58b..d825de164c 100644
--- a/src/castable.h
+++ b/src/castable.h
@@ -196,8 +196,14 @@ class CastableBase {
   /// Copy constructor
   CastableBase(const CastableBase&) = default;
 
+  /// Destructor
   virtual ~CastableBase() = default;
 
+  /// Copy assignment
+  /// @param other the CastableBase to copy
+  /// @returns the new CastableBase
+  CastableBase& operator=(const CastableBase& other) = default;
+
   /// @returns the TypeInfo of the object
   virtual const tint::TypeInfo& TypeInfo() const = 0;