diff --git a/scripts/emitted-baseline-runtime.txt b/scripts/emitted-baseline-runtime.txt
index 7a4c385a..e881bc49 100644
--- a/scripts/emitted-baseline-runtime.txt
+++ b/scripts/emitted-baseline-runtime.txt
@@ -946,6 +946,7 @@ object-integrity-uses-physical-index-protocol.runtime.ts.cpp 23551c4185ed
 object-is-over-union-and-optional-carriers.runtime.ts.cpp 199c1035ac10
 object-key-enumeration-requires-native-object.runtime.ts.cpp f6c110078688
 object-keyed-map-index-matches-node.runtime.ts.cpp ab5c357ecdd6
+object-keys-over-recursive-dictionary-or-array-union.runtime.ts.cpp 061e846e55a7
 object-literal-beside-class-in-or-keeps-its-own-layout.runtime.ts.cpp d86094099c83
 object-literal-empty-array-filled-through-untyped-computed-read.runtime.js.cpp d13b67ac0d25
 object-literal-es5-method-receiver.runtime.js.cpp 4c1c19bfe47a
diff --git a/src/targets/cpp/runtime/gea_runtime.h b/src/targets/cpp/runtime/gea_runtime.h
index ddf5d293..6de309da 100644
--- a/src/targets/cpp/runtime/gea_runtime.h
+++ b/src/targets/cpp/runtime/gea_runtime.h
@@ -15981,6 +15981,15 @@ struct ArrayObjectElementOf<ArrayObject<Element>> {
   using type = Element;
 };
 
+namespace detail {
+template <typename Element>
+ArrayObject<Element> arrayObjectBaseProbe(const ArrayObject<Element>&);
+template <typename T>
+using ArrayObjectBaseOf = decltype(arrayObjectBaseProbe(std::declval<const T&>()));
+template <typename T>
+concept DerivedArrayObject = !IsArrayObjectStruct<T>::value && requires { typename ArrayObjectBaseOf<T>; };
+}
+
 namespace detail {
 template <typename T>
 struct DynamicCarrier;
@@ -32639,6 +32648,26 @@ bool assignOwnPropertiesUnorderedWith(const gea::Ref<T>& source, const gea::Ref<
 }
 
 /** Array exotic own enumerable string keys, followed by enumerable expandos. */
+template <typename Element>
+std::vector<std::string> arrayOwnEnumerableKeys(const gea::Ref<ArrayObject<Element>>& array);
+template <typename Element>
+bool arrayHasOwnEnumerableKey(const gea::Ref<ArrayObject<Element>>& array, const std::string& key);
+template <typename Element>
+std::vector<std::string> arrayOwnPropertyNames(const gea::Ref<ArrayObject<Element>>& array);
+
+template <detail::DerivedArrayObject Array>
+std::vector<std::string> arrayOwnEnumerableKeys(const gea::Ref<Array>& array) {
+  return arrayOwnEnumerableKeys(gea::Ref<detail::ArrayObjectBaseOf<Array>>(array));
+}
+template <detail::DerivedArrayObject Array>
+bool arrayHasOwnEnumerableKey(const gea::Ref<Array>& array, const std::string& key) {
+  return arrayHasOwnEnumerableKey(gea::Ref<detail::ArrayObjectBaseOf<Array>>(array), key);
+}
+template <detail::DerivedArrayObject Array>
+std::vector<std::string> arrayOwnPropertyNames(const gea::Ref<Array>& array) {
+  return arrayOwnPropertyNames(gea::Ref<detail::ArrayObjectBaseOf<Array>>(array));
+}
+
 template <typename Element>
 std::vector<std::string> arrayOwnEnumerableKeys(const gea::Ref<ArrayObject<Element>>& array) {
   std::vector<std::string> keys;
diff --git a/test/runtime/object-keys-over-recursive-dictionary-or-array-union.runtime.ts b/test/runtime/object-keys-over-recursive-dictionary-or-array-union.runtime.ts
new file mode 100644
index 00000000..ab8e8e1e
--- /dev/null
+++ b/test/runtime/object-keys-over-recursive-dictionary-or-array-union.runtime.ts
@@ -0,0 +1,16 @@
+type Leaf = string
+type Tree = { [key: string]: Leaf | Tree | Branch }
+type Branch = (Leaf | Tree | Branch | undefined)[]
+type Container = Tree | Branch
+
+const keysOf = (container: Container): string => Object.keys(container).join(',')
+
+const tree: Tree = { a: 'x', b: ['y', { c: 'z' }] }
+const branch: Branch = ['p', tree, undefined, 'q']
+tree['self'] = branch
+
+console.log(keysOf(tree))
+console.log(keysOf(branch))
+
+//! expect: a,b,self
+//! expect: 0,1,2,3