diff --git a/modules/gdnative/gdnative/aabb.cpp b/modules/gdnative/gdnative/aabb.cpp
index 246e5d4e8d2..7f22c7dfe34 100644
--- a/modules/gdnative/gdnative/aabb.cpp
+++ b/modules/gdnative/gdnative/aabb.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_aabb) == sizeof(AABB), "AABB size mismatch");
+
 void GDAPI godot_aabb_new(godot_aabb *r_dest, const godot_vector3 *p_pos, const godot_vector3 *p_size) {
 	const Vector3 *pos = (const Vector3 *)p_pos;
 	const Vector3 *size = (const Vector3 *)p_size;
diff --git a/modules/gdnative/gdnative/array.cpp b/modules/gdnative/gdnative/array.cpp
index 4a0308edecd..01acce05b90 100644
--- a/modules/gdnative/gdnative/array.cpp
+++ b/modules/gdnative/gdnative/array.cpp
@@ -42,6 +42,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_array) == sizeof(Array), "Array size mismatch");
+
 void GDAPI godot_array_new(godot_array *r_dest) {
 	Array *dest = (Array *)r_dest;
 	memnew_placement(dest, Array);
diff --git a/modules/gdnative/gdnative/basis.cpp b/modules/gdnative/gdnative/basis.cpp
index 4f489287b99..990fd3795d1 100644
--- a/modules/gdnative/gdnative/basis.cpp
+++ b/modules/gdnative/gdnative/basis.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_basis) == sizeof(Basis), "Basis size mismatch");
+
 void GDAPI godot_basis_new_with_rows(godot_basis *r_dest, const godot_vector3 *p_x_axis, const godot_vector3 *p_y_axis, const godot_vector3 *p_z_axis) {
 	const Vector3 *x_axis = (const Vector3 *)p_x_axis;
 	const Vector3 *y_axis = (const Vector3 *)p_y_axis;
diff --git a/modules/gdnative/gdnative/color.cpp b/modules/gdnative/gdnative/color.cpp
index 24587ce4a14..5049549a05f 100644
--- a/modules/gdnative/gdnative/color.cpp
+++ b/modules/gdnative/gdnative/color.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_color) == sizeof(Color), "Color size mismatch");
+
 void GDAPI godot_color_new_rgba(godot_color *r_dest, const godot_real p_r, const godot_real p_g, const godot_real p_b, const godot_real p_a) {
 
 	Color *dest = (Color *)r_dest;
diff --git a/modules/gdnative/gdnative/dictionary.cpp b/modules/gdnative/gdnative/dictionary.cpp
index b145b88934b..a1269748151 100644
--- a/modules/gdnative/gdnative/dictionary.cpp
+++ b/modules/gdnative/gdnative/dictionary.cpp
@@ -39,6 +39,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_dictionary) == sizeof(Dictionary), "Dictionary size mismatch");
+
 void GDAPI godot_dictionary_new(godot_dictionary *r_dest) {
 	Dictionary *dest = (Dictionary *)r_dest;
 	memnew_placement(dest, Dictionary);
diff --git a/modules/gdnative/gdnative/node_path.cpp b/modules/gdnative/gdnative/node_path.cpp
index 93f43835c88..88ed650ebee 100644
--- a/modules/gdnative/gdnative/node_path.cpp
+++ b/modules/gdnative/gdnative/node_path.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_node_path) == sizeof(NodePath), "NodePath size mismatch");
+
 void GDAPI godot_node_path_new(godot_node_path *r_dest, const godot_string *p_from) {
 	NodePath *dest = (NodePath *)r_dest;
 	const String *from = (const String *)p_from;
diff --git a/modules/gdnative/gdnative/plane.cpp b/modules/gdnative/gdnative/plane.cpp
index 17221fe0815..0eef49e30ca 100644
--- a/modules/gdnative/gdnative/plane.cpp
+++ b/modules/gdnative/gdnative/plane.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_plane) == sizeof(Plane), "Plane size mismatch");
+
 void GDAPI godot_plane_new_with_reals(godot_plane *r_dest, const godot_real p_a, const godot_real p_b, const godot_real p_c, const godot_real p_d) {
 
 	Plane *dest = (Plane *)r_dest;
diff --git a/modules/gdnative/gdnative/pool_arrays.cpp b/modules/gdnative/gdnative/pool_arrays.cpp
index bae1290d59f..8d929b2cc05 100644
--- a/modules/gdnative/gdnative/pool_arrays.cpp
+++ b/modules/gdnative/gdnative/pool_arrays.cpp
@@ -42,6 +42,14 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_pool_byte_array) == sizeof(PoolVector<uint8_t>), "PoolVector<uint8_t> size mismatch");
+static_assert(sizeof(godot_pool_int_array) == sizeof(PoolVector<godot_int>), "PoolVector<godot_int> size mismatch");
+static_assert(sizeof(godot_pool_real_array) == sizeof(PoolVector<godot_real>), "PoolVector<godot_real> size mismatch");
+static_assert(sizeof(godot_pool_string_array) == sizeof(PoolVector<String>), "PoolVector<String> size mismatch");
+static_assert(sizeof(godot_pool_vector2_array) == sizeof(PoolVector<Vector2>), "PoolVector<Vector2> size mismatch");
+static_assert(sizeof(godot_pool_vector3_array) == sizeof(PoolVector<Vector3>), "PoolVector<Vector3> size mismatch");
+static_assert(sizeof(godot_pool_color_array) == sizeof(PoolVector<Color>), "PoolVector<Color> size mismatch");
+
 #define memnew_placement_custom(m_placement, m_class, m_constr) _post_initialize(new (m_placement, sizeof(m_class), "") m_constr)
 
 // byte
diff --git a/modules/gdnative/gdnative/quat.cpp b/modules/gdnative/gdnative/quat.cpp
index be30b89e5fe..a8708847f87 100644
--- a/modules/gdnative/gdnative/quat.cpp
+++ b/modules/gdnative/gdnative/quat.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_quat) == sizeof(Quat), "Quat size mismatch");
+
 void GDAPI godot_quat_new(godot_quat *r_dest, const godot_real p_x, const godot_real p_y, const godot_real p_z, const godot_real p_w) {
 
 	Quat *dest = (Quat *)r_dest;
diff --git a/modules/gdnative/gdnative/rect2.cpp b/modules/gdnative/gdnative/rect2.cpp
index 906b4f09326..d489d0d8413 100644
--- a/modules/gdnative/gdnative/rect2.cpp
+++ b/modules/gdnative/gdnative/rect2.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_rect2) == sizeof(Rect2), "Rect2 size mismatch");
+
 void GDAPI godot_rect2_new_with_position_and_size(godot_rect2 *r_dest, const godot_vector2 *p_pos, const godot_vector2 *p_size) {
 	const Vector2 *position = (const Vector2 *)p_pos;
 	const Vector2 *size = (const Vector2 *)p_size;
diff --git a/modules/gdnative/gdnative/rid.cpp b/modules/gdnative/gdnative/rid.cpp
index 7ea80123a3d..d7a63f33a72 100644
--- a/modules/gdnative/gdnative/rid.cpp
+++ b/modules/gdnative/gdnative/rid.cpp
@@ -38,6 +38,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_rid) == sizeof(RID), "RID size mismatch");
+
 void GDAPI godot_rid_new(godot_rid *r_dest) {
 	RID *dest = (RID *)r_dest;
 	memnew_placement(dest, RID);
diff --git a/modules/gdnative/gdnative/string.cpp b/modules/gdnative/gdnative/string.cpp
index 414b9b9eaf2..79a23c3dda2 100644
--- a/modules/gdnative/gdnative/string.cpp
+++ b/modules/gdnative/gdnative/string.cpp
@@ -40,6 +40,10 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_char_string) == sizeof(CharString), "CharString size mismatch");
+static_assert(sizeof(godot_string) == sizeof(String), "String size mismatch");
+static_assert(sizeof(godot_char_type) == sizeof(CharType), "CharType size mismatch");
+
 godot_int GDAPI godot_char_string_length(const godot_char_string *p_cs) {
 	const CharString *cs = (const CharString *)p_cs;
 
diff --git a/modules/gdnative/gdnative/string_name.cpp b/modules/gdnative/gdnative/string_name.cpp
index 1abb4486b1d..7bbaaeeaa03 100644
--- a/modules/gdnative/gdnative/string_name.cpp
+++ b/modules/gdnative/gdnative/string_name.cpp
@@ -39,6 +39,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_string_name) == sizeof(StringName), "StringName size mismatch");
+
 void GDAPI godot_string_name_new(godot_string_name *r_dest, const godot_string *p_name) {
 	StringName *dest = (StringName *)r_dest;
 	const String *name = (const String *)p_name;
diff --git a/modules/gdnative/gdnative/transform.cpp b/modules/gdnative/gdnative/transform.cpp
index c9b3e37fb2e..d19de93e9b8 100644
--- a/modules/gdnative/gdnative/transform.cpp
+++ b/modules/gdnative/gdnative/transform.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_transform) == sizeof(Transform), "Transform size mismatch");
+
 void GDAPI godot_transform_new_with_axis_origin(godot_transform *r_dest, const godot_vector3 *p_x_axis, const godot_vector3 *p_y_axis, const godot_vector3 *p_z_axis, const godot_vector3 *p_origin) {
 	const Vector3 *x_axis = (const Vector3 *)p_x_axis;
 	const Vector3 *y_axis = (const Vector3 *)p_y_axis;
diff --git a/modules/gdnative/gdnative/transform2d.cpp b/modules/gdnative/gdnative/transform2d.cpp
index 26a71333b14..c0f7878eb09 100644
--- a/modules/gdnative/gdnative/transform2d.cpp
+++ b/modules/gdnative/gdnative/transform2d.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_transform2d) == sizeof(Transform2D), "Transform2D size mismatch");
+
 void GDAPI godot_transform2d_new(godot_transform2d *r_dest, const godot_real p_rot, const godot_vector2 *p_pos) {
 	const Vector2 *pos = (const Vector2 *)p_pos;
 	Transform2D *dest = (Transform2D *)r_dest;
diff --git a/modules/gdnative/gdnative/variant.cpp b/modules/gdnative/gdnative/variant.cpp
index 11b6448e340..ccf85e35292 100644
--- a/modules/gdnative/gdnative/variant.cpp
+++ b/modules/gdnative/gdnative/variant.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_variant) == sizeof(Variant), "Variant size mismatch");
+
 // Workaround GCC ICE on armv7hl which was affected GCC 6.0 up to 8.0 (GH-16100).
 // It was fixed upstream in 8.1, and a fix was backported to 7.4.
 // This can be removed once no supported distro ships with versions older than 7.4.
diff --git a/modules/gdnative/gdnative/vector2.cpp b/modules/gdnative/gdnative/vector2.cpp
index e9e2a8edf83..5331f1be6e1 100644
--- a/modules/gdnative/gdnative/vector2.cpp
+++ b/modules/gdnative/gdnative/vector2.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_vector2) == sizeof(Vector2), "Vector2 size mismatch");
+
 void GDAPI godot_vector2_new(godot_vector2 *r_dest, const godot_real p_x, const godot_real p_y) {
 
 	Vector2 *dest = (Vector2 *)r_dest;
diff --git a/modules/gdnative/gdnative/vector3.cpp b/modules/gdnative/gdnative/vector3.cpp
index e34a9370a57..89351a12ad0 100644
--- a/modules/gdnative/gdnative/vector3.cpp
+++ b/modules/gdnative/gdnative/vector3.cpp
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+static_assert(sizeof(godot_vector3) == sizeof(Vector3), "Vector3 size mismatch");
+
 void GDAPI godot_vector3_new(godot_vector3 *r_dest, const godot_real p_x, const godot_real p_y, const godot_real p_z) {
 
 	Vector3 *dest = (Vector3 *)r_dest;
diff --git a/modules/gdnative/include/gdnative/variant.h b/modules/gdnative/include/gdnative/variant.h
index c65f7a28d2b..5da6d97181e 100644
--- a/modules/gdnative/include/gdnative/variant.h
+++ b/modules/gdnative/include/gdnative/variant.h
@@ -37,7 +37,7 @@ extern "C" {
 
 #include <stdint.h>
 
-#define GODOT_VARIANT_SIZE (16 + sizeof(void *))
+#define GODOT_VARIANT_SIZE (16 + sizeof(int64_t))
 
 #ifndef GODOT_CORE_API_GODOT_VARIANT_TYPE_DEFINED
 #define GODOT_CORE_API_GODOT_VARIANT_TYPE_DEFINED