diff --git a/CMakeLists.txt b/CMakeLists.txt
index 04854e740..b222eca73 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.16.3) # version on Ubuntu Focal
 
-project(behaviortree_cpp VERSION 4.9.1 LANGUAGES C CXX)
+project(behaviortree_cpp VERSION 4.10.0 LANGUAGES C CXX)
 
 # create compile_commands.json
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
diff --git a/include/behaviortree_cpp/actions/test_node.h b/include/behaviortree_cpp/actions/test_node.h
index c675d2e4c..9e571500d 100644
--- a/include/behaviortree_cpp/actions/test_node.h
+++ b/include/behaviortree_cpp/actions/test_node.h
@@ -15,6 +15,11 @@
 
 #include "behaviortree_cpp/action_node.h"
 
+// Not used by this header anymore, but included since 4.x: kept so that
+// consumers relying on them transitively do not break.
+#include "behaviortree_cpp/scripting/script_parser.hpp"  // IWYU pragma: keep
+#include "behaviortree_cpp/utils/timer_queue.h"          // IWYU pragma: keep
+
 #include <chrono>
 #include <functional>
 #include <memory>
@@ -112,8 +117,12 @@ class TestNode : public BT::StatefulActionNode
 
   NodeStatus onCompleted();
 
-  // All state lives behind this pointer, so that adding or changing it does not
-  // alter the layout that consumers compile against.
+  // Kept as a direct member (first, at the same offset as in 4.9) for
+  // compatibility with subclasses that access it. Everything else lives behind
+  // the PImpl, so that adding or changing state does not alter the layout that
+  // consumers compile against.
+  std::shared_ptr<TestNodeConfig> _config;
+
   struct PImpl;
   std::unique_ptr<PImpl> _p;
 };
diff --git a/package.xml b/package.xml
index 4d5d2fe03..3ab80bc66 100644
--- a/package.xml
+++ b/package.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <package format="3">
   <name>behaviortree_cpp</name>
-  <version>4.9.1</version>
+  <version>4.10.0</version>
   <description>
   This package provides the Behavior Trees core library.
   </description>
diff --git a/src/actions/test_node.cpp b/src/actions/test_node.cpp
index 6990ffe14..a1f91d0fc 100644
--- a/src/actions/test_node.cpp
+++ b/src/actions/test_node.cpp
@@ -79,7 +79,6 @@ NodeStatus convertScriptResultToStatus(const Any& result)
 
 struct TestNode::PImpl
 {
-  std::shared_ptr<TestNodeConfig> config;
   ScriptFunction return_status_executor;
   ScriptFunction success_executor;
   ScriptFunction failure_executor;
@@ -95,14 +94,15 @@ TestNode::TestNode(const std::string& name, const NodeConfig& config,
 
 TestNode::TestNode(const std::string& name, const NodeConfig& config,
                    std::shared_ptr<TestNodeConfig> test_config)
-  : StatefulActionNode(name, config), _p(std::make_unique<PImpl>())
+  : StatefulActionNode(name, config)
+  , _config(std::move(test_config))
+  , _p(std::make_unique<PImpl>())
 {
-  _p->config = std::move(test_config);
   setRegistrationID("TestNode");
 
-  if(_p->config->return_status_script.empty())
+  if(_config->return_status_script.empty())
   {
-    validateTestNodeStatus(_p->config->return_status, "return_status");
+    validateTestNodeStatus(_config->return_status, "return_status");
   }
 
   auto prepareScript = [](const std::string& script, auto& executor) {
@@ -116,24 +116,24 @@ TestNode::TestNode(const std::string& name, const NodeConfig& config,
       executor = result.value();
     }
   };
-  prepareScript(_p->config->return_status_script, _p->return_status_executor);
-  prepareScript(_p->config->success_script, _p->success_executor);
-  prepareScript(_p->config->failure_script, _p->failure_executor);
-  prepareScript(_p->config->post_script, _p->post_executor);
+  prepareScript(_config->return_status_script, _p->return_status_executor);
+  prepareScript(_config->success_script, _p->success_executor);
+  prepareScript(_config->failure_script, _p->failure_executor);
+  prepareScript(_config->post_script, _p->post_executor);
 }
 
 TestNode::~TestNode() = default;
 
 NodeStatus TestNode::onStart()
 {
-  if(_p->config->async_delay <= std::chrono::milliseconds(0))
+  if(_config->async_delay <= std::chrono::milliseconds(0))
   {
     return onCompleted();
   }
   // convert this in an asynchronous operation. Use another thread to count
   // a certain amount of time.
   _p->completed = false;
-  _p->timer.add(std::chrono::milliseconds(_p->config->async_delay), [this](bool aborted) {
+  _p->timer.add(std::chrono::milliseconds(_config->async_delay), [this](bool aborted) {
     if(!aborted)
     {
       _p->completed.store(true);
@@ -165,9 +165,9 @@ NodeStatus TestNode::onCompleted()
 {
   NodeStatus status = NodeStatus::IDLE;
 
-  if(_p->config->complete_func)
+  if(_config->complete_func)
   {
-    status = _p->config->complete_func();
+    status = _config->complete_func();
   }
   else if(_p->return_status_executor)
   {
@@ -180,7 +180,7 @@ NodeStatus TestNode::onCompleted()
   }
   else
   {
-    status = _p->config->return_status;
+    status = _config->return_status;
   }
 
   validateTestNodeStatus(status, "completion");