diff --git a/src/client/camera.h b/src/client/camera.h
index 1018af55a7ba..cd6c89a96b5e 100644
--- a/src/client/camera.h
+++ b/src/client/camera.h
@@ -22,6 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irrlichttypes_extrabloated.h"
 #include "inventory.h"
 #include "client/tile.h"
+#include "client/localplayer.h"
 #include <ICameraSceneNode.h>
 #include <ISceneNode.h>
 #include <plane3d.h>
diff --git a/src/client/client.cpp b/src/client/client.cpp
index 054c7d2ac896..b2d71d0575b6 100644
--- a/src/client/client.cpp
+++ b/src/client/client.cpp
@@ -32,6 +32,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/renderingengine.h"
 #include "client/sound.h"
 #include "client/tile.h"
+#include "client/mesh_generator_thread.h"
+#include "client/particles.h"
+#include "client/localplayer.h"
 #include "util/auth.h"
 #include "util/directiontables.h"
 #include "util/pointedthing.h"
@@ -60,6 +63,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "chatmessage.h"
 #include "translation.h"
 #include "content/mod_configuration.h"
+#include "mapnode.h"
 
 extern gui::IGUIEnvironment* guienv;
 
@@ -112,12 +116,12 @@ Client::Client(
 	m_sound(sound),
 	m_event(event),
 	m_rendering_engine(rendering_engine),
-	m_mesh_update_manager(this),
+	m_mesh_update_manager(std::make_unique<MeshUpdateManager>(this)),
 	m_env(
 		new ClientMap(this, rendering_engine, control, 666),
 		tsrc, this
 	),
-	m_particle_manager(&m_env),
+	m_particle_manager(std::make_unique<ParticleManager>(&m_env)),
 	m_con(new con::Connection(PROTOCOL_ID, 512, CONNECTION_TIMEOUT, ipv6, this)),
 	m_address_name(address_name),
 	m_allow_login_or_register(allow_login_or_register),
@@ -314,7 +318,7 @@ void Client::Stop()
 	if (m_mods_loaded)
 		m_script->on_shutdown();
 	//request all client managed threads to stop
-	m_mesh_update_manager.stop();
+	m_mesh_update_manager->stop();
 	// Save local server map
 	if (m_localdb) {
 		infostream << "Local map saving ended." << std::endl;
@@ -327,7 +331,7 @@ void Client::Stop()
 
 bool Client::isShutdown()
 {
-	return m_shutdown || !m_mesh_update_manager.isRunning();
+	return m_shutdown || !m_mesh_update_manager->isRunning();
 }
 
 Client::~Client()
@@ -337,11 +341,11 @@ Client::~Client()
 
 	deleteAuthData();
 
-	m_mesh_update_manager.stop();
-	m_mesh_update_manager.wait();
+	m_mesh_update_manager->stop();
+	m_mesh_update_manager->wait();
 
 	MeshUpdateResult r;
-	while (m_mesh_update_manager.getNextResult(r)) {
+	while (m_mesh_update_manager->getNextResult(r)) {
 		for (auto block : r.map_blocks)
 			if (block)
 				block->refDrop();
@@ -553,7 +557,7 @@ void Client::step(float dtime)
 		std::vector<v3s16> blocks_to_ack;
 		bool force_update_shadows = false;
 		MeshUpdateResult r;
-		while (m_mesh_update_manager.getNextResult(r))
+		while (m_mesh_update_manager->getNextResult(r))
 		{
 			num_processed_meshes++;
 
@@ -1128,12 +1132,14 @@ void Client::startAuth(AuthMechanism chosen_auth_mechanism)
 {
 	m_chosen_auth_mech = chosen_auth_mechanism;
 
+	std::string playername = m_env.getLocalPlayer()->getName();
+
 	switch (chosen_auth_mechanism) {
 		case AUTH_MECHANISM_FIRST_SRP: {
 			// send srp verifier to server
 			std::string verifier;
 			std::string salt;
-			generate_srp_verifier_and_salt(getPlayerName(), m_password,
+			generate_srp_verifier_and_salt(playername, m_password,
 				&verifier, &salt);
 
 			NetworkPacket resp_pkt(TOSERVER_FIRST_SRP, 0);
@@ -1147,13 +1153,13 @@ void Client::startAuth(AuthMechanism chosen_auth_mechanism)
 			u8 based_on = 1;
 
 			if (chosen_auth_mechanism == AUTH_MECHANISM_LEGACY_PASSWORD) {
-				m_password = translate_password(getPlayerName(), m_password);
+				m_password = translate_password(playername, m_password);
 				based_on = 0;
 			}
 
-			std::string playername_u = lowercase(getPlayerName());
+			std::string playername_u = lowercase(playername);
 			m_auth_data = srp_user_new(SRP_SHA256, SRP_NG_2048,
-				getPlayerName().c_str(), playername_u.c_str(),
+				playername.c_str(), playername_u.c_str(),
 				(const unsigned char *) m_password.c_str(),
 				m_password.length(), NULL, NULL);
 			char *bytes_A = 0;
@@ -1695,12 +1701,12 @@ void Client::addUpdateMeshTask(v3s16 p, bool ack_to_server, bool urgent)
 	if (b == NULL)
 		return;
 
-	m_mesh_update_manager.updateBlock(&m_env.getMap(), p, ack_to_server, urgent);
+	m_mesh_update_manager->updateBlock(&m_env.getMap(), p, ack_to_server, urgent);
 }
 
 void Client::addUpdateMeshTaskWithEdge(v3s16 blockpos, bool ack_to_server, bool urgent)
 {
-	m_mesh_update_manager.updateBlock(&m_env.getMap(), blockpos, ack_to_server, urgent, true);
+	m_mesh_update_manager->updateBlock(&m_env.getMap(), blockpos, ack_to_server, urgent, true);
 }
 
 void Client::addUpdateMeshTaskForNode(v3s16 nodepos, bool ack_to_server, bool urgent)
@@ -1714,7 +1720,7 @@ void Client::addUpdateMeshTaskForNode(v3s16 nodepos, bool ack_to_server, bool ur
 
 	v3s16 blockpos = getNodeBlockPos(nodepos);
 	v3s16 blockpos_relative = blockpos * MAP_BLOCKSIZE;
-	m_mesh_update_manager.updateBlock(&m_env.getMap(), blockpos, ack_to_server, urgent, false);
+	m_mesh_update_manager->updateBlock(&m_env.getMap(), blockpos, ack_to_server, urgent, false);
 	// Leading edge
 	if (nodepos.X == blockpos_relative.X)
 		addUpdateMeshTask(blockpos + v3s16(-1, 0, 0), false, urgent);
@@ -1724,6 +1730,11 @@ void Client::addUpdateMeshTaskForNode(v3s16 nodepos, bool ack_to_server, bool ur
 		addUpdateMeshTask(blockpos + v3s16(0, 0, -1), false, urgent);
 }
 
+void Client::updateCameraOffset(v3s16 camera_offset)
+{
+	m_mesh_update_manager->m_camera_offset = camera_offset;
+}
+
 ClientEvent *Client::getClientEvent()
 {
 	FATAL_ERROR_IF(m_client_event_queue.empty(),
@@ -1828,7 +1839,7 @@ void Client::afterContentReceived()
 
 	// Start mesh update thread after setting up content definitions
 	infostream<<"- Starting mesh update thread"<<std::endl;
-	m_mesh_update_manager.start();
+	m_mesh_update_manager->start();
 
 	m_state = LC_Ready;
 	sendReady();
@@ -1979,7 +1990,7 @@ MtEventManager* Client::getEventManager()
 
 ParticleManager* Client::getParticleManager()
 {
-	return &m_particle_manager;
+	return m_particle_manager.get();
 }
 
 scene::IAnimatedMesh* Client::getMesh(const std::string &filename, bool cache)
@@ -2078,3 +2089,8 @@ ModChannel* Client::getModChannel(const std::string &channel)
 {
 	return m_modchannel_mgr->getModChannel(channel);
 }
+
+const std::string &Client::getFormspecPrepend() const
+{
+	return m_env.getLocalPlayer()->formspec_prepend;
+}
diff --git a/src/client/client.h b/src/client/client.h
index 5ed5c6e9a28a..585af2fd3d76 100644
--- a/src/client/client.h
+++ b/src/client/client.h
@@ -23,18 +23,15 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irrlichttypes_extrabloated.h"
 #include <ostream>
 #include <map>
+#include <memory>
 #include <set>
 #include <vector>
 #include <unordered_set>
 #include "clientobject.h"
 #include "gamedef.h"
 #include "inventorymanager.h"
-#include "localplayer.h"
 #include "client/hud.h"
-#include "particles.h"
-#include "mapnode.h"
 #include "tileanimation.h"
-#include "mesh_generator_thread.h"
 #include "network/address.h"
 #include "network/peerhandler.h"
 #include "gameparams.h"
@@ -61,10 +58,14 @@ struct MapDrawControl;
 class ModChannelMgr;
 class MtEventManager;
 struct PointedThing;
+struct MapNode;
 class MapDatabase;
 class Minimap;
 struct MinimapMapblock;
+class MeshUpdateManager;
+class ParticleManager;
 class Camera;
+struct PlayerControl;
 class NetworkPacket;
 namespace con {
 class Connection;
@@ -315,8 +316,7 @@ class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 	void addUpdateMeshTaskWithEdge(v3s16 blockpos, bool ack_to_server=false, bool urgent=false);
 	void addUpdateMeshTaskForNode(v3s16 nodepos, bool ack_to_server=false, bool urgent=false);
 
-	void updateCameraOffset(v3s16 camera_offset)
-	{ m_mesh_update_manager.m_camera_offset = camera_offset; }
+	void updateCameraOffset(v3s16 camera_offset);
 
 	bool hasClientEvents() const { return !m_client_event_queue.empty(); }
 	// Get event from queue. If queue is empty, it triggers an assertion failure.
@@ -436,10 +436,7 @@ class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 			const std::string &message) override;
 	ModChannel *getModChannel(const std::string &channel) override;
 
-	const std::string &getFormspecPrepend() const
-	{
-		return m_env.getLocalPlayer()->formspec_prepend;
-	}
+	const std::string &getFormspecPrepend() const;
 	inline MeshGrid getMeshGrid()
 	{
 		return m_mesh_grid;
@@ -470,10 +467,6 @@ class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 	void sendGotBlocks(const std::vector<v3s16> &blocks);
 	void sendRemovedSounds(std::vector<s32> &soundList);
 
-	// Helper function
-	inline std::string getPlayerName()
-	{ return m_env.getLocalPlayer()->getName(); }
-
 	bool canSendChatMessage() const;
 
 	float m_packetcounter_timer = 0.0f;
@@ -491,9 +484,9 @@ class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 	RenderingEngine *m_rendering_engine;
 
 
-	MeshUpdateManager m_mesh_update_manager;
+	std::unique_ptr<MeshUpdateManager> m_mesh_update_manager;
 	ClientEnvironment m_env;
-	ParticleManager m_particle_manager;
+	std::unique_ptr<ParticleManager> m_particle_manager;
 	std::unique_ptr<con::Connection> m_con;
 	std::string m_address_name;
 	ELoginRegister m_allow_login_or_register = ELoginRegister::Any;
diff --git a/src/client/clientenvironment.cpp b/src/client/clientenvironment.cpp
index d9b88eb4a54b..69c8ac00bdc8 100644
--- a/src/client/clientenvironment.cpp
+++ b/src/client/clientenvironment.cpp
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "clientenvironment.h"
 #include "clientsimpleobject.h"
 #include "clientmap.h"
+#include "localplayer.h"
 #include "scripting_client.h"
 #include "mapblock_mesh.h"
 #include "mtevent.h"
diff --git a/src/client/clientmap.cpp b/src/client/clientmap.cpp
index e99e6b89d8fc..00fd4b133827 100644
--- a/src/client/clientmap.cpp
+++ b/src/client/clientmap.cpp
@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <matrix4.h>
 #include "mapsector.h"
 #include "mapblock.h"
+#include "nodedef.h"
 #include "profiler.h"
 #include "settings.h"
 #include "camera.h"               // CameraModes
diff --git a/src/client/content_cao.cpp b/src/client/content_cao.cpp
index 230edc222fb9..76a0b63dcd7a 100644
--- a/src/client/content_cao.cpp
+++ b/src/client/content_cao.cpp
@@ -26,6 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/renderingengine.h"
 #include "client/sound.h"
 #include "client/tile.h"
+#include "client/mapblock_mesh.h"
 #include "util/basic_macros.h"
 #include "util/numeric.h"
 #include "util/serialize.h"
diff --git a/src/client/game.cpp b/src/client/game.cpp
index 5d630a01dd79..18b3f9ec9d3f 100644
--- a/src/client/game.cpp
+++ b/src/client/game.cpp
@@ -30,6 +30,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/tile.h"     // For TextureSource
 #include "client/keys.h"
 #include "client/joystick_controller.h"
+#include "client/mapblock_mesh.h"
 #include "clientmap.h"
 #include "clouds.h"
 #include "config.h"
diff --git a/src/client/mapblock_mesh.cpp b/src/client/mapblock_mesh.cpp
index 23db42c5577b..10eb1f5cd80b 100644
--- a/src/client/mapblock_mesh.cpp
+++ b/src/client/mapblock_mesh.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client.h"
 #include "mapblock.h"
 #include "map.h"
+#include "noise.h"
 #include "profiler.h"
 #include "shader.h"
 #include "mesh.h"
@@ -31,6 +32,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/renderingengine.h"
 #include <array>
 #include <algorithm>
+#include <cmath>
 
 /*
 	MeshMakeData
diff --git a/src/client/render/pipeline.cpp b/src/client/render/pipeline.cpp
index 3e5347e376f1..8fccc7808bb9 100644
--- a/src/client/render/pipeline.cpp
+++ b/src/client/render/pipeline.cpp
@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "pipeline.h"
 #include "client/client.h"
 #include "client/hud.h"
+#include "IRenderTarget.h"
 
 #include <vector>
 #include <memory>
@@ -63,7 +64,7 @@ void TextureBuffer::setTexture(u8 index, v2f scale_factor, const std::string &na
 
 	if (m_definitions.size() <= index)
 		m_definitions.resize(index + 1);
-	
+
 	auto &definition = m_definitions[index];
 	definition.valid = true;
 	definition.dirty = true;
@@ -99,7 +100,7 @@ void TextureBuffer::reset(PipelineContext &context)
 		ensureTexture(ptr, m_definitions[i], context);
 		m_definitions[i].dirty = false;
 	}
-	
+
 	RenderSource::reset(context);
 }
 
@@ -124,7 +125,7 @@ bool TextureBuffer::ensureTexture(video::ITexture **texture, const TextureDefini
 			size = core::dimension2du(
 					(u32)(context.target_size.X * definition.scale_factor.X),
 					(u32)(context.target_size.Y * definition.scale_factor.Y));
-		
+
 		modify = definition.dirty || (*texture == nullptr) || (*texture)->getSize() != size;
 	}
 	else {
@@ -283,7 +284,7 @@ void RenderPipeline::run(PipelineContext &context)
 
 	for (auto &step: m_pipeline)
 		step->run(context);
-	
+
 	context.target_size = original_size;
 }
 
diff --git a/src/client/render/secondstage.cpp b/src/client/render/secondstage.cpp
index 1575cfb1fff4..ee8d41c387b8 100644
--- a/src/client/render/secondstage.cpp
+++ b/src/client/render/secondstage.cpp
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/client.h"
 #include "client/shader.h"
 #include "client/tile.h"
+#include "settings.h"
 
 PostProcessingStep::PostProcessingStep(u32 _shader_id, const std::vector<u8> &_texture_map) :
 	shader_id(_shader_id), texture_map(_texture_map)
diff --git a/src/client/shadows/dynamicshadowsrender.cpp b/src/client/shadows/dynamicshadowsrender.cpp
index 320a046cda0a..688bfae1d462 100644
--- a/src/client/shadows/dynamicshadowsrender.cpp
+++ b/src/client/shadows/dynamicshadowsrender.cpp
@@ -29,6 +29,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/client.h"
 #include "client/clientmap.h"
 #include "profiler.h"
+#include "EShaderTypes.h"
+#include "IGPUProgrammingServices.h"
+#include "IMaterialRenderer.h"
 
 ShadowRenderer::ShadowRenderer(IrrlichtDevice *device, Client *client) :
 		m_smgr(device->getSceneManager()), m_driver(device->getVideoDriver()),
diff --git a/src/environment.h b/src/environment.h
index b4884fdb3849..19c30b4d5ae2 100644
--- a/src/environment.h
+++ b/src/environment.h
@@ -35,8 +35,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <atomic>
 #include <mutex>
 #include "irr_v3d.h"
-#include "network/networkprotocol.h" // for AccessDeniedCode
 #include "util/basic_macros.h"
+#include "line3d.h"
 
 class IGameDef;
 class Map;
diff --git a/src/gui/guiFormSpecMenu.h b/src/gui/guiFormSpecMenu.h
index 36a84c13c00e..02d4f1a1937d 100644
--- a/src/gui/guiFormSpecMenu.h
+++ b/src/gui/guiFormSpecMenu.h
@@ -25,6 +25,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "irrlichttypes_extrabloated.h"
 #include "irr_ptr.h"
+#include "inventory.h"
 #include "inventorymanager.h"
 #include "modalMenu.h"
 #include "guiInventoryList.h"
diff --git a/src/gui/guiHyperText.cpp b/src/gui/guiHyperText.cpp
index 233a7e63587d..c2241c944fbe 100644
--- a/src/gui/guiHyperText.cpp
+++ b/src/gui/guiHyperText.cpp
@@ -25,6 +25,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/client.h"
 #include "client/renderingengine.h"
 #include "hud.h"
+#include "inventory.h"
 #include "util/string.h"
 #include "irrlicht_changes/CGUITTFont.h"
 
diff --git a/src/gui/guiItemImage.cpp b/src/gui/guiItemImage.cpp
index f93d5476c98a..a02285fcbf94 100644
--- a/src/gui/guiItemImage.cpp
+++ b/src/gui/guiItemImage.cpp
@@ -19,6 +19,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "guiItemImage.h"
 #include "client/client.h"
+#include "inventory.h"
 
 GUIItemImage::GUIItemImage(gui::IGUIEnvironment *env, gui::IGUIElement *parent,
 	s32 id, const core::rect<s32> &rectangle, const std::string &item_name,
diff --git a/src/inventory.cpp b/src/inventory.cpp
index 43f45a2d4065..eb7133b41a12 100644
--- a/src/inventory.cpp
+++ b/src/inventory.cpp
@@ -23,7 +23,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <algorithm>
 #include <sstream>
 #include "log.h"
-#include "itemdef.h"
 #include "util/strfnd.h"
 #include "content_mapnode.h" // For loading legacy MaterialItems
 #include "nameidmapping.h" // For loading legacy MaterialItems
diff --git a/src/inventorymanager.cpp b/src/inventorymanager.cpp
index 782a17112d62..1c6b3ffc9f06 100644
--- a/src/inventorymanager.cpp
+++ b/src/inventorymanager.cpp
@@ -28,6 +28,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "rollback_interface.h"
 #include "util/strfnd.h"
 #include "util/basic_macros.h"
+#include "inventory.h"
 
 #define PLAYER_TO_SA(p)   p->getEnv()->getScriptIface()
 
diff --git a/src/inventorymanager.h b/src/inventorymanager.h
index 4ad5d3f49ae0..246ad2947427 100644
--- a/src/inventorymanager.h
+++ b/src/inventorymanager.h
@@ -19,10 +19,15 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
-#include "inventory.h"
+#include "irr_v3d.h"
 #include <iostream>
 #include <string>
+#include <vector>
+
 class ServerActiveObject;
+struct ItemStack;
+class Inventory;
+class IGameDef;
 
 struct InventoryLocation
 {
diff --git a/src/mapblock.h b/src/mapblock.h
index d2ffc4bb7077..f0491e25ce36 100644
--- a/src/mapblock.h
+++ b/src/mapblock.h
@@ -30,7 +30,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "modifiedstate.h"
 #include "util/numeric.h" // getContainerPos
 #include "settings.h"
-#include "mapgen/mapgen.h"
 
 class Map;
 class NodeMetadataList;
diff --git a/src/network/clientpackethandler.cpp b/src/network/clientpackethandler.cpp
index 942f101fcad3..48524553e50e 100644
--- a/src/network/clientpackethandler.cpp
+++ b/src/network/clientpackethandler.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "util/base64.h"
 #include "client/camera.h"
+#include "client/mesh_generator_thread.h"
 #include "chatmessage.h"
 #include "client/clientmedia.h"
 #include "log.h"
@@ -30,12 +31,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "modchannels.h"
 #include "nodedef.h"
 #include "serialization.h"
-#include "server.h"
 #include "util/strfnd.h"
 #include "client/clientevent.h"
 #include "client/sound.h"
 #include "network/clientopcodes.h"
 #include "network/connection.h"
+#include "network/networkpacket.h"
 #include "script/scripting_client.h"
 #include "util/serialize.h"
 #include "util/srp.h"
@@ -43,6 +44,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "tileanimation.h"
 #include "gettext.h"
 #include "skyparams.h"
+#include "particles.h"
 #include <memory>
 
 void Client::handleCommand_Deprecated(NetworkPacket* pkt)
@@ -672,7 +674,7 @@ void Client::handleCommand_AnnounceMedia(NetworkPacket* pkt)
 
 	// Mesh update thread must be stopped while
 	// updating content definitions
-	sanity_check(!m_mesh_update_manager.isRunning());
+	sanity_check(!m_mesh_update_manager->isRunning());
 
 	for (u16 i = 0; i < num_files; i++) {
 		std::string name, sha1_base64;
@@ -732,7 +734,7 @@ void Client::handleCommand_Media(NetworkPacket* pkt)
 	if (init_phase) {
 		// Mesh update thread must be stopped while
 		// updating content definitions
-		sanity_check(!m_mesh_update_manager.isRunning());
+		sanity_check(!m_mesh_update_manager->isRunning());
 	}
 
 	for (u32 i = 0; i < num_files; i++) {
@@ -769,7 +771,7 @@ void Client::handleCommand_NodeDef(NetworkPacket* pkt)
 
 	// Mesh update thread must be stopped while
 	// updating content definitions
-	sanity_check(!m_mesh_update_manager.isRunning());
+	sanity_check(!m_mesh_update_manager->isRunning());
 
 	// Decompress node definitions
 	std::istringstream tmp_is(pkt->readLongString(), std::ios::binary);
@@ -788,7 +790,7 @@ void Client::handleCommand_ItemDef(NetworkPacket* pkt)
 
 	// Mesh update thread must be stopped while
 	// updating content definitions
-	sanity_check(!m_mesh_update_manager.isRunning());
+	sanity_check(!m_mesh_update_manager->isRunning());
 
 	// Decompress item definitions
 	std::istringstream tmp_is(pkt->readLongString(), std::ios::binary);
diff --git a/src/script/cpp_api/s_client.cpp b/src/script/cpp_api/s_client.cpp
index b937c9f7be39..6faa0695c38a 100644
--- a/src/script/cpp_api/s_client.cpp
+++ b/src/script/cpp_api/s_client.cpp
@@ -23,6 +23,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "client/client.h"
 #include "common/c_converter.h"
 #include "common/c_content.h"
+#include "lua_api/l_item.h"
+#include "itemdef.h"
 #include "s_item.h"
 
 void ScriptApiClient::on_mods_loaded()
diff --git a/src/script/cpp_api/s_client.h b/src/script/cpp_api/s_client.h
index 93fe96791c57..8a5523d0d328 100644
--- a/src/script/cpp_api/s_client.h
+++ b/src/script/cpp_api/s_client.h
@@ -20,19 +20,19 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
-#include "util/pointedthing.h"
 #include "cpp_api/s_base.h"
 #include "mapnode.h"
-#include "itemdef.h"
 #include "util/string.h"
 #include "util/pointedthing.h"
-#include "lua_api/l_item.h"
 
 #ifdef _CRT_MSVCP_CURRENT
 #include <cstdint>
 #endif
 
 class ClientEnvironment;
+struct ItemStack;
+class Inventory;
+struct ItemDefinition;
 
 class ScriptApiClient : virtual public ScriptApiBase
 {
diff --git a/src/script/cpp_api/s_modchannels.cpp b/src/script/cpp_api/s_modchannels.cpp
index caff3f05e57e..e2fa0dfec95b 100644
--- a/src/script/cpp_api/s_modchannels.cpp
+++ b/src/script/cpp_api/s_modchannels.cpp
@@ -19,6 +19,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "s_modchannels.h"
 #include "s_internal.h"
+#include "modchannels.h"
 
 void ScriptApiModChannels::on_modchannel_message(const std::string &channel,
 		const std::string &sender, const std::string &message)
diff --git a/src/script/cpp_api/s_modchannels.h b/src/script/cpp_api/s_modchannels.h
index 4de7a8291d0c..d8295076230b 100644
--- a/src/script/cpp_api/s_modchannels.h
+++ b/src/script/cpp_api/s_modchannels.h
@@ -20,7 +20,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include "cpp_api/s_base.h"
-#include "modchannels.h"
+
+enum ModChannelSignal : u8;
 
 class ScriptApiModChannels : virtual public ScriptApiBase
 {
diff --git a/src/server.cpp b/src/server.cpp
index 5e5f96360e93..e8c3daaacc92 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -73,6 +73,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "database/database-files.h"
 #include "database/database-dummy.h"
 #include "gameparams.h"
+#include "particles.h"
 
 class ClientNotFoundException : public BaseException
 {
diff --git a/src/server.h b/src/server.h
index 9ce3cc24dc8b..e8865fbef0b0 100644
--- a/src/server.h
+++ b/src/server.h
@@ -27,8 +27,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "content/mods.h"
 #include "inventorymanager.h"
 #include "content/subgames.h"
-#include "tileanimation.h" // TileAnimationParams
-#include "particles.h" // ParticleParams
 #include "network/peerhandler.h"
 #include "network/address.h"
 #include "util/numeric.h"
@@ -38,6 +36,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "serverenvironment.h"
 #include "clientiface.h"
 #include "chatmessage.h"
+#include "sound.h"
 #include "translation.h"
 #include <string>
 #include <list>
@@ -74,6 +73,8 @@ class ServerThread;
 class ServerModManager;
 class ServerInventoryManager;
 struct PackedValue;
+struct ParticleParameters;
+struct ParticleSpawnerParameters;
 
 enum ClientDeletionReason {
 	CDR_LEAVE,
diff --git a/src/server/luaentity_sao.cpp b/src/server/luaentity_sao.cpp
index 5624c0f55126..3b6ef1fbacc0 100644
--- a/src/server/luaentity_sao.cpp
+++ b/src/server/luaentity_sao.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "luaentity_sao.h"
 #include "collision.h"
 #include "constants.h"
+#include "inventory.h"
 #include "player_sao.h"
 #include "scripting_server.h"
 #include "server.h"
@@ -409,7 +410,7 @@ void LuaEntitySAO::setHP(s32 hp, const PlayerHPChangeReason &reason)
 			m_env->getScriptIface()->luaentity_on_death(m_id, killer);
 		}
 		markForRemoval();
-	}	
+	}
 }
 
 u16 LuaEntitySAO::getHP() const
diff --git a/src/server/player_sao.h b/src/server/player_sao.h
index 6d8498d8d0c6..973a415a31c6 100644
--- a/src/server/player_sao.h
+++ b/src/server/player_sao.h
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include "constants.h"
+#include "metadata.h"
 #include "network/networkprotocol.h"
 #include "unit_sao.h"
 #include "util/numeric.h"
diff --git a/src/server/serveractiveobject.cpp b/src/server/serveractiveobject.cpp
index 96b433d1d106..fb09464cfbb4 100644
--- a/src/server/serveractiveobject.cpp
+++ b/src/server/serveractiveobject.cpp
@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "serveractiveobject.h"
 #include <fstream>
 #include "inventory.h"
+#include "inventorymanager.h"
 #include "constants.h" // BS
 #include "log.h"
 
@@ -89,3 +90,8 @@ void ServerActiveObject::markForDeactivation()
 		m_pending_deactivation = true;
 	}
 }
+
+InventoryLocation ServerActiveObject::getInventoryLocation() const
+{
+	return InventoryLocation();
+}
diff --git a/src/server/serveractiveobject.h b/src/server/serveractiveobject.h
index 5b0ee2d9b312..568295e29d61 100644
--- a/src/server/serveractiveobject.h
+++ b/src/server/serveractiveobject.h
@@ -19,10 +19,10 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
+#include <cassert>
 #include <unordered_set>
 #include "irrlichttypes_bloated.h"
 #include "activeobject.h"
-#include "inventorymanager.h"
 #include "itemgroup.h"
 #include "util/container.h"
 
@@ -47,6 +47,8 @@ struct ItemStack;
 struct ToolCapabilities;
 struct ObjectProperties;
 struct PlayerHPChangeReason;
+class Inventory;
+struct InventoryLocation;
 
 class ServerActiveObject : public ActiveObject
 {
@@ -184,8 +186,7 @@ class ServerActiveObject : public ActiveObject
 	// Inventory and wielded item
 	virtual Inventory *getInventory() const
 	{ return NULL; }
-	virtual InventoryLocation getInventoryLocation() const
-	{ return InventoryLocation(); }
+	virtual InventoryLocation getInventoryLocation() const;
 	virtual void setInventoryModified()
 	{}
 	virtual std::string getWieldList() const
diff --git a/src/server/serverinventorymgr.h b/src/server/serverinventorymgr.h
index 0e4b7241537e..ce1af41be33f 100644
--- a/src/server/serverinventorymgr.h
+++ b/src/server/serverinventorymgr.h
@@ -20,8 +20,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include "inventorymanager.h"
+#include <cassert>
 #include <functional>
+#include <unordered_map>
 
+class IItemDefManager;
 class ServerEnvironment;
 
 class ServerInventoryManager : public InventoryManager
diff --git a/src/server/unit_sao.cpp b/src/server/unit_sao.cpp
index 6fdefaad47a1..54d4a029d281 100644
--- a/src/server/unit_sao.cpp
+++ b/src/server/unit_sao.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "unit_sao.h"
 #include "scripting_server.h"
 #include "serverenvironment.h"
+#include "util/serialize.h"
 
 UnitSAO::UnitSAO(ServerEnvironment *env, v3f pos) : ServerActiveObject(env, pos)
 {
diff --git a/src/serverenvironment.h b/src/serverenvironment.h
index bb40a33ce221..312b282021eb 100644
--- a/src/serverenvironment.h
+++ b/src/serverenvironment.h
@@ -41,6 +41,8 @@ struct StaticObject;
 class ServerActiveObject;
 class Server;
 class ServerScripting;
+enum AccessDeniedCode : u8;
+typedef u16 session_t;
 
 /*
 	{Active, Loading} block modifier interface.
diff --git a/src/unittest/mock_inventorymanager.h b/src/unittest/mock_inventorymanager.h
index 0cbf8c70760a..dc75490de38d 100644
--- a/src/unittest/mock_inventorymanager.h
+++ b/src/unittest/mock_inventorymanager.h
@@ -18,6 +18,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include <gamedef.h>
+#include <inventory.h>
 #include <inventorymanager.h>
 
 class MockInventoryManager : public InventoryManager
diff --git a/src/unittest/test_voxelalgorithms.cpp b/src/unittest/test_voxelalgorithms.cpp
index 767e9de31e93..8caa0fbf40d1 100644
--- a/src/unittest/test_voxelalgorithms.cpp
+++ b/src/unittest/test_voxelalgorithms.cpp
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "voxelalgorithms.h"
 #include "util/numeric.h"
 #include "dummymap.h"
+#include "nodedef.h"
 
 class TestVoxelAlgorithms : public TestBase {
 public: