diff --git a/tests/test_tagbased_polymorphic.cpp b/tests/test_tagbased_polymorphic.cpp
index 272e460c9..dcc005126 100644
--- a/tests/test_tagbased_polymorphic.cpp
+++ b/tests/test_tagbased_polymorphic.cpp
@@ -12,6 +12,12 @@
 
 struct Animal
 {
+    // Make this type also a "standard" polymorphic type, to confirm that
+    // specializing polymorphic_type_hook using enable_if_t still works
+    // (https://github.com/pybind/pybind11/pull/2016/).
+    virtual ~Animal() = default;
+
+    // Enum for tag-based polymorphism.
     enum class Kind {
         Unknown = 0,
         Dog = 100, Labrador, Chihuahua, LastDog = 199,