diff --git a/src/openrct2/actions/BannerSetNameAction.hpp b/src/openrct2/actions/BannerSetNameAction.hpp
index e7b61c0b18..4375813a8b 100644
--- a/src/openrct2/actions/BannerSetNameAction.hpp
+++ b/src/openrct2/actions/BannerSetNameAction.hpp
@@ -19,6 +19,7 @@
 #include "../Context.h"
 #include "../core/String.hpp"
 #include "../drawing/Drawing.h"
+#include "../localisation/Localisation.h"
 #include "../localisation/StringIds.h"
 #include "../ui/UiContext.h"
 #include "../world/Sprite.h"
diff --git a/src/openrct2/actions/MazeSetTrackAction.hpp b/src/openrct2/actions/MazeSetTrackAction.hpp
index 82a4312004..0c2b10a9dd 100644
--- a/src/openrct2/actions/MazeSetTrackAction.hpp
+++ b/src/openrct2/actions/MazeSetTrackAction.hpp
@@ -26,6 +26,7 @@
 #include "../management/Finance.h"
 #include "../ride/Track.h"
 #include "../ride/TrackData.h"
+#include "../world/Footpath.h"
 #include "../world/Park.h"
 
 /** rct2: 0x00993CE9 */
diff --git a/src/openrct2/actions/ParkSetNameAction.hpp b/src/openrct2/actions/ParkSetNameAction.hpp
index 0e9cd59a91..fab0d9bd9b 100644
--- a/src/openrct2/actions/ParkSetNameAction.hpp
+++ b/src/openrct2/actions/ParkSetNameAction.hpp
@@ -18,6 +18,7 @@
 
 #include "../Context.h"
 #include "../drawing/Drawing.h"
+#include "../localisation/Localisation.h"
 #include "../localisation/StringIds.h"
 #include "../ui/UiContext.h"
 #include "../world/Sprite.h"
diff --git a/src/openrct2/actions/PlacePeepSpawnAction.hpp b/src/openrct2/actions/PlacePeepSpawnAction.hpp
index 5b5d6c58af..9bbbf34266 100644
--- a/src/openrct2/actions/PlacePeepSpawnAction.hpp
+++ b/src/openrct2/actions/PlacePeepSpawnAction.hpp
@@ -22,6 +22,7 @@
 #include "GameAction.h"
 
 #include "../Cheats.h"
+#include "../management/Finance.h"
 #include "../world/Park.h"
 #include "../world/Footpath.h"
 
diff --git a/src/openrct2/actions/RideDemolishAction.hpp b/src/openrct2/actions/RideDemolishAction.hpp
index 5948fbd4d3..11d52aca94 100644
--- a/src/openrct2/actions/RideDemolishAction.hpp
+++ b/src/openrct2/actions/RideDemolishAction.hpp
@@ -21,9 +21,12 @@
 #include "../core/MemoryStream.h"
 #include "../interface/Window.h"
 #include "../localisation/Localisation.h"
+#include "../management/NewsItem.h"
 #include "../ride/Ride.h"
 #include "../ui/UiContext.h"
 #include "../ui/WindowManager.h"
+#include "../world/Banner.h"
+#include "../world/Sprite.h"
 #include "../world/Park.h"
 #include "GameAction.h"
 #include "MazeSetTrackAction.hpp"
diff --git a/src/openrct2/actions/RideSetName.hpp b/src/openrct2/actions/RideSetName.hpp
index 329faaa659..9f61a87a9d 100644
--- a/src/openrct2/actions/RideSetName.hpp
+++ b/src/openrct2/actions/RideSetName.hpp
@@ -19,9 +19,11 @@
 #include "../Cheats.h"
 #include "../Context.h"
 #include "../core/MemoryStream.h"
+#include "../drawing/Drawing.h"
 #include "../interface/Window.h"
 #include "../localisation/Localisation.h"
 #include "../localisation/StringIds.h"
+#include "../ride/Ride.h"
 #include "../ui/UiContext.h"
 #include "../ui/WindowManager.h"
 #include "../world/Park.h"
diff --git a/src/openrct2/actions/RideSetStatus.hpp b/src/openrct2/actions/RideSetStatus.hpp
index ee22f50e36..f953ba80a6 100644
--- a/src/openrct2/actions/RideSetStatus.hpp
+++ b/src/openrct2/actions/RideSetStatus.hpp
@@ -16,13 +16,17 @@
 
 #pragma once
 
+#include "../common.h"
 #include "../core/MemoryStream.h"
+#include "../localisation/Localisation.h"
 #include "../localisation/StringIds.h"
 #include "GameAction.h"
 
 #include "../Cheats.h"
 #include "../interface/Window.h"
+#include "../management/Finance.h"
 #include "../world/Park.h"
+#include "../world/Sprite.h"
 #include "../ride/Ride.h"
 
 static rct_string_id _StatusErrorTitles[] =
diff --git a/src/openrct2/actions/SignSetNameAction.hpp b/src/openrct2/actions/SignSetNameAction.hpp
index e5440d2e68..6b952b6449 100644
--- a/src/openrct2/actions/SignSetNameAction.hpp
+++ b/src/openrct2/actions/SignSetNameAction.hpp
@@ -18,6 +18,7 @@
 
 #include "../Context.h"
 #include "../drawing/Drawing.h"
+#include "../localisation/Localisation.h"
 #include "../localisation/StringIds.h"
 #include "../ui/UiContext.h"
 #include "../world/Sprite.h"
diff --git a/src/openrct2/actions/StaffSetNameAction.hpp b/src/openrct2/actions/StaffSetNameAction.hpp
index b270a500fe..8fdfecdd00 100644
--- a/src/openrct2/actions/StaffSetNameAction.hpp
+++ b/src/openrct2/actions/StaffSetNameAction.hpp
@@ -22,11 +22,13 @@
 
 #include "../Cheats.h"
 #include "../Context.h"
+#include "../drawing/Drawing.h"
 #include "../peep/Staff.h"
 #include "../interface/Window.h"
 #include "../localisation/Localisation.h"
 #include "../windows/Intent.h"
 #include "../world/Park.h"
+#include "../world/Sprite.h"
 
 struct StaffSetNameAction : public GameActionBase<GAME_COMMAND_SET_STAFF_NAME, GameActionResult>
 {
diff --git a/src/openrct2/core/Zip.h b/src/openrct2/core/Zip.h
index 8d3e85efd0..c1add665c4 100644
--- a/src/openrct2/core/Zip.h
+++ b/src/openrct2/core/Zip.h
@@ -18,6 +18,8 @@
 
 #include "../common.h"
 
+interface IStream;
+
 /**
  * Represents a zip file.
  */
diff --git a/src/openrct2/drawing/NewDrawing.h b/src/openrct2/drawing/NewDrawing.h
index 37a5205ee4..244bd3fca3 100644
--- a/src/openrct2/drawing/NewDrawing.h
+++ b/src/openrct2/drawing/NewDrawing.h
@@ -19,6 +19,7 @@
 #include "../common.h"
 
 struct rct_drawpixelinfo;
+struct rct_palette_entry;
 
 extern rct_string_id DrawingEngineStringIds[3];
 
diff --git a/src/openrct2/drawing/Rain.h b/src/openrct2/drawing/Rain.h
index 97bfb60c91..552057ef5a 100644
--- a/src/openrct2/drawing/Rain.h
+++ b/src/openrct2/drawing/Rain.h
@@ -18,6 +18,8 @@
 
 #include "../common.h"
 
+struct rct_drawpixelinfo;
+
 namespace OpenRCT2 { namespace Drawing
 {
     interface IRainDrawer;
diff --git a/src/openrct2/interface/Window_internal.h b/src/openrct2/interface/Window_internal.h
index dddd97823f..30845f4a1e 100644
--- a/src/openrct2/interface/Window_internal.h
+++ b/src/openrct2/interface/Window_internal.h
@@ -17,6 +17,8 @@
 #ifndef _WINDOW2_H_
 #define _WINDOW2_H_
 
+#include "Window.h"
+
 struct rct_research_item;
 struct rct_object_entry;
 
diff --git a/src/openrct2/localisation/FormatCodes.h b/src/openrct2/localisation/FormatCodes.h
index 6cc7224a61..e7d0d518cf 100644
--- a/src/openrct2/localisation/FormatCodes.h
+++ b/src/openrct2/localisation/FormatCodes.h
@@ -17,6 +17,8 @@
 #ifndef _FORMAT_CODES_H_
 #define _FORMAT_CODES_H_
 
+#include "../common.h"
+
 uint32 format_get_code(const char *token);
 const char *format_get_token(uint32 code);
 
diff --git a/src/openrct2/network/NetworkKey.h b/src/openrct2/network/NetworkKey.h
index 91a97395f5..eb5e9275f4 100644
--- a/src/openrct2/network/NetworkKey.h
+++ b/src/openrct2/network/NetworkKey.h
@@ -21,6 +21,7 @@
 
 #include "../common.h"
 #include <string>
+#include <openssl/evp.h>
 
 using EVP_PKEY     = evp_pkey_st;
 using EVP_PKEY_CTX = evp_pkey_ctx_st;
diff --git a/src/openrct2/object/ObjectFactory.h b/src/openrct2/object/ObjectFactory.h
index c8b1793f1d..5db5444e41 100644
--- a/src/openrct2/object/ObjectFactory.h
+++ b/src/openrct2/object/ObjectFactory.h
@@ -19,6 +19,7 @@
 #include "../common.h"
 
 class Object;
+struct rct_object_entry;
 
 namespace ObjectFactory
 {
diff --git a/src/openrct2/paint/VirtualFloor.h b/src/openrct2/paint/VirtualFloor.h
index 7c20c27a29..771d1e8115 100644
--- a/src/openrct2/paint/VirtualFloor.h
+++ b/src/openrct2/paint/VirtualFloor.h
@@ -17,6 +17,8 @@
 #ifndef _VIRTUAL_FLOOR_H
 #define _VIRTUAL_FLOOR_H
 
+#include "../common.h"
+
 struct paint_session;
 
 uint16 virtual_floor_get_height();
diff --git a/src/openrct2/ride/VehiclePaint.h b/src/openrct2/ride/VehiclePaint.h
index b953029d62..eca7be6918 100644
--- a/src/openrct2/ride/VehiclePaint.h
+++ b/src/openrct2/ride/VehiclePaint.h
@@ -17,7 +17,11 @@
 #ifndef _VEHICLE_PAINT_H
 #define _VEHICLE_PAINT_H
 
-#include "Vehicle.h"
+#include "../common.h"
+
+struct paint_session;
+struct rct_ride_entry_vehicle;
+struct rct_vehicle;
 
 struct vehicle_boundbox {
     sint8 offset_x;
diff --git a/src/openrct2/ride/coaster/BolligerMabillardTrack.h b/src/openrct2/ride/coaster/BolligerMabillardTrack.h
index a538f417b2..b59e43c746 100644
--- a/src/openrct2/ride/coaster/BolligerMabillardTrack.h
+++ b/src/openrct2/ride/coaster/BolligerMabillardTrack.h
@@ -16,6 +16,11 @@
 
 #pragma once
 
+#include "../../common.h"
+
+struct paint_session;
+struct rct_tile_element;
+
 void bolliger_mabillard_track_flat(
     paint_session *          session,
     uint8                    rideIndex,
diff --git a/src/openrct2/title/TitleSequencePlayer.h b/src/openrct2/title/TitleSequencePlayer.h
index ea61e68c0f..864a2cb5b0 100644
--- a/src/openrct2/title/TitleSequencePlayer.h
+++ b/src/openrct2/title/TitleSequencePlayer.h
@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include "../common.h"
+
 interface IScenarioRepository;
 
 interface ITitleSequencePlayer
diff --git a/src/openrct2/world/MapHelpers.h b/src/openrct2/world/MapHelpers.h
index 53d4b80b17..b17d4f0a87 100644
--- a/src/openrct2/world/MapHelpers.h
+++ b/src/openrct2/world/MapHelpers.h
@@ -17,6 +17,8 @@
 #ifndef _MAP_HELPERS_H_
 #define _MAP_HELPERS_H_
 
+#include "../common.h"
+
 enum {
     SLOPE_S_THRESHOLD_FLAGS = (1 << 0),
     SLOPE_W_THRESHOLD_FLAGS = (1 << 1),