diff --git a/source/scriptinterface/ScriptInterface.cpp b/source/scriptinterface/ScriptInterface.cpp
index 1092b147f3..95b6394afe 100644
--- a/source/scriptinterface/ScriptInterface.cpp
+++ b/source/scriptinterface/ScriptInterface.cpp
@@ -704,6 +704,36 @@ bool ScriptInterface::HasProperty(JS::HandleValue obj, const char* name) const
 	return found;
 }
 
+bool ScriptInterface::GetGlobalProperty(const ScriptRequest& rq, const std::string& name, JS::MutableHandleValue out)
+{
+	// Try to get the object as a property of the global object.
+	JS::RootedObject global(rq.cx, rq.glob);
+	if (!JS_GetProperty(rq.cx, global, name.c_str(), out))
+	{
+		out.set(JS::NullHandleValue);
+		return false;
+	}
+
+	if (!out.isNullOrUndefined())
+		return true;
+
+	// Some objects, such as const definitions, or Class definitions, are hidden inside closures.
+	// We must fetch those from the correct lexical scope.
+	//JS::RootedValue glob(cx);
+	JS::RootedObject lexical_environment(rq.cx, JS_GlobalLexicalEnvironment(rq.glob));
+	if (!JS_GetProperty(rq.cx, lexical_environment, name.c_str(), out))
+	{
+		out.set(JS::NullHandleValue);
+		return false;
+	}
+
+	if (!out.isNullOrUndefined())
+		return true;
+
+	out.set(JS::NullHandleValue);
+	return false;
+}
+
 bool ScriptInterface::EnumeratePropertyNames(JS::HandleValue objVal, bool enumerableOnly, std::vector<std::string>& out) const
 {
 	ScriptRequest rq(this);
diff --git a/source/scriptinterface/ScriptInterface.h b/source/scriptinterface/ScriptInterface.h
index f5279581ff..15670c45b9 100644
--- a/source/scriptinterface/ScriptInterface.h
+++ b/source/scriptinterface/ScriptInterface.h
@@ -233,6 +233,15 @@ public:
 	 */
 	bool HasProperty(JS::HandleValue obj, const char* name) const;
 
+	/**
+	 * Get an object from the global scope or any lexical scope.
+	 * This can return globally accessible objects even if they are not properties
+	 * of the global object (e.g. ES6 class definitions).
+	 * @param name - Name of the property.
+	 * @param out The object or null.
+	 */
+	static bool GetGlobalProperty(const ScriptRequest& rq, const std::string& name, JS::MutableHandleValue out);
+
 	/**
 	 * Returns all properties of the object, both own properties and inherited.
 	 * This is essentially equivalent to calling Object.getOwnPropertyNames()
diff --git a/source/simulation2/scripting/EngineScriptConversions.cpp b/source/simulation2/scripting/EngineScriptConversions.cpp
index 511a3309c9..5c12f9f16b 100644
--- a/source/simulation2/scripting/EngineScriptConversions.cpp
+++ b/source/simulation2/scripting/EngineScriptConversions.cpp
@@ -160,7 +160,7 @@ template<> void ScriptInterface::ToJSVal<CFixedVector3D>(const ScriptRequest& rq
 {
 	JS::RootedObject global(rq.cx, rq.glob);
 	JS::RootedValue valueVector3D(rq.cx);
-	if (!JS_GetProperty(rq.cx, global, "Vector3D", &valueVector3D))
+	if (!ScriptInterface::GetGlobalProperty(rq, "Vector3D", &valueVector3D))
 		FAIL_VOID("Failed to get Vector3D constructor");
 
 	JS::RootedValueArray<3> args(rq.cx);
@@ -196,7 +196,7 @@ template<> void ScriptInterface::ToJSVal<CFixedVector2D>(const ScriptRequest& rq
 {
 	JS::RootedObject global(rq.cx, rq.glob);
 	JS::RootedValue valueVector2D(rq.cx);
-	if (!JS_GetProperty(rq.cx, global, "Vector2D", &valueVector2D))
+	if (!ScriptInterface::GetGlobalProperty(rq, "Vector2D", &valueVector2D))
 		FAIL_VOID("Failed to get Vector2D constructor");
 
 	JS::RootedValueArray<2> args(rq.cx);