diff --git a/README.md b/README.md
index 33c4cd7..df1e96a 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 This is a c++ engine module for the Godot engine, containing my mesh merging utilities.
 
-It supports both godot 3.2 and 4.0 (master). Note that since 4.0 is still in very early stages I only 
+It supports both godot 3.2 and 4.0 (master [last tested commit](https://github.com/godotengine/godot/commit/b7e10141197fdd9b0dbc4cfa7890329510d36540)). Note that since 4.0 is still in very early stages I only 
 check whether it works from time to time.
 
 # Pre-built binaries
diff --git a/defines.h b/defines.h
index 22db1f9..7255650 100644
--- a/defines.h
+++ b/defines.h
@@ -18,7 +18,7 @@
 #define light_h "scene/3d/light_3d.h"
 #define visual_server_h "servers/rendering_server.h"
 #define mesh_instance_h "scene/3d/mesh_instance_3d.h"
-#define pool_vector_h "core/vector.h"
+#define pool_vector_h "core/templates/vector.h"
 #define physics_server_h "servers/physics_server_3d.h"
 #define immediate_geometry_h "scene/3d/immediate_geometry_3d.h"
 #define include_pool_vector \
diff --git a/fast_quadratic_mesh_simplifier.h b/fast_quadratic_mesh_simplifier.h
index 437d907..ebd4cd9 100644
--- a/fast_quadratic_mesh_simplifier.h
+++ b/fast_quadratic_mesh_simplifier.h
@@ -25,9 +25,15 @@ SOFTWARE.
 
 */
 
-#include "core/reference.h"
+#include "core/version.h"
 
+#if VERSION_MAJOR > 3
+#include "core/object/reference.h"
+#include "core/variant/array.h"
+#else
+#include "core/reference.h"
 #include "core/array.h"
+#endif
 
 #include "simplify.h"
 
diff --git a/mesh_merger.h b/mesh_merger.h
index a164a67..8c8de75 100644
--- a/mesh_merger.h
+++ b/mesh_merger.h
@@ -25,7 +25,17 @@ SOFTWARE.
 #ifndef MESH_MERGER_H
 #define MESH_MERGER_H
 
+#include "core/version.h"
+
+#if VERSION_MAJOR > 3
+#include "core/object/reference.h"
+#include "core/templates/vector.h"
+#include "core/math/color.h"
+#else
 #include "core/reference.h"
+#include "core/vector.h"
+#include "core/color.h"
+#endif
 
 #include "defines.h"
 
@@ -34,11 +44,9 @@ include_pool_vector
 
 #include mesh_instance_h
 
-#include "core/color.h"
 #include "core/math/rect2.h"
 #include "core/math/vector2.h"
 #include "core/math/vector3.h"
-#include "core/vector.h"
 #include "scene/main/node.h"
 #include "scene/resources/material.h"
 #include "scene/resources/mesh.h"
diff --git a/mesh_utils.h b/mesh_utils.h
index 2f9a7b6..75b4f92 100644
--- a/mesh_utils.h
+++ b/mesh_utils.h
@@ -23,7 +23,13 @@ SOFTWARE.
 #ifndef MESH_UTILS_H
 #define MESH_UTILS_H
 
+#include "core/version.h"
+
+#if VERSION_MAJOR > 3
+#include "core/object/object.h"
+#else
 #include "core/object.h"
+#endif
 
 #include "scene/resources/texture.h"
 
diff --git a/register_types.cpp b/register_types.cpp
index 2bfc690..5b3a301 100644
--- a/register_types.cpp
+++ b/register_types.cpp
@@ -24,7 +24,14 @@ SOFTWARE.
 
 #include "register_types.h"
 
+#include "core/version.h"
+
+#if VERSION_MAJOR > 3
+#include "core/config/engine.h"
+#else
 #include "core/engine.h"
+#endif
+
 #include "fast_quadratic_mesh_simplifier.h"
 #include "mesh_merger.h"
 #include "mesh_utils.h"
diff --git a/simplify.h b/simplify.h
index 6aedfa9..75b0d2f 100644
--- a/simplify.h
+++ b/simplify.h
@@ -14,10 +14,18 @@
 //
 // 5/2016: Chris Rorden created minimal version for OSX/Linux/Windows compile
 
+#include "core/version.h"
+
+#if VERSION_MAJOR > 3
+#include "core/string/ustring.h"
+#include "core/variant/array.h"
+#else
+#include "core/ustring.h"
 #include "core/array.h"
+#endif
+
 #include "core/math/vector2.h"
 #include "core/math/vector3.h"
-#include "core/ustring.h"
 #include "scene/resources/mesh.h"
 
 #include <float.h> //FLT_EPSILON, DBL_EPSILON