diff --git a/src/openrct2-ui/UiContext.cpp b/src/openrct2-ui/UiContext.cpp
index da0e0fd590..c059ac162d 100644
--- a/src/openrct2-ui/UiContext.cpp
+++ b/src/openrct2-ui/UiContext.cpp
@@ -30,7 +30,6 @@
 #include <openrct2/drawing/Drawing.h>
 #include <openrct2/localisation/StringIds.h>
 #include <openrct2/interface/Chat.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/platform/Platform2.h>
 #include <openrct2/ui/UiContext.h>
 #include <openrct2/ui/WindowManager.h>
@@ -38,6 +37,7 @@
 #include "CursorRepository.h"
 #include "drawing/engines/DrawingEngineFactory.hpp"
 #include "input/KeyboardShortcuts.h"
+#include "interface/Theme.h"
 #include "SDLException.h"
 #include "TextComposition.h"
 #include "UiContext.h"
diff --git a/src/openrct2-ui/WindowManager.cpp b/src/openrct2-ui/WindowManager.cpp
index 1625f38692..e9070949f0 100644
--- a/src/openrct2-ui/WindowManager.cpp
+++ b/src/openrct2-ui/WindowManager.cpp
@@ -18,12 +18,12 @@
 #include <openrct2-ui/windows/Window.h>
 #include <openrct2/core/Console.hpp>
 #include <openrct2/config/Config.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/interface/Viewport.h>
 #include <openrct2/Input.h>
 #include <openrct2/world/Sprite.h>
 #include "input/Input.h"
 #include "input/KeyboardShortcuts.h"
+#include "interface/Theme.h"
 #include "WindowManager.h"
 #include "windows/Window.h"
 
diff --git a/src/openrct2-ui/interface/InGameConsole.cpp b/src/openrct2-ui/interface/InGameConsole.cpp
index f1415ba5ab..2a93e30036 100644
--- a/src/openrct2-ui/interface/InGameConsole.cpp
+++ b/src/openrct2-ui/interface/InGameConsole.cpp
@@ -5,12 +5,12 @@
 #include <openrct2/core/Math.hpp>
 #include <openrct2/drawing/Drawing.h>
 #include <openrct2/interface/Colour.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/interface/Window.h>
 #include <openrct2/localisation/Language.h>
 #include <openrct2/localisation/LocalisationService.h>
 #include <openrct2/Version.h>
 #include "InGameConsole.h"
+#include "Theme.h"
 
 using namespace OpenRCT2::Ui;
 
diff --git a/src/openrct2/interface/Theme.cpp b/src/openrct2-ui/interface/Theme.cpp
similarity index 98%
rename from src/openrct2/interface/Theme.cpp
rename to src/openrct2-ui/interface/Theme.cpp
index fbc15371f2..b78aad3bc6 100644
--- a/src/openrct2/interface/Theme.cpp
+++ b/src/openrct2-ui/interface/Theme.cpp
@@ -21,24 +21,23 @@
 #include <vector>
 #include <jansson.h>
 
-#include "../common.h"
-#include "../config/Config.h"
-#include "../Context.h"
-#include "../core/File.h"
-#include "../core/FileScanner.h"
-#include "../core/Guard.hpp"
-#include "../core/Json.hpp"
-#include "../core/Math.hpp"
-#include "../core/Path.hpp"
-#include "../core/String.hpp"
-#include "../drawing/Drawing.h"
-#include "../localisation/Language.h"
-#include "../localisation/StringIds.h"
-#include "../PlatformEnvironment.h"
-#include "themes.h"
+#include <openrct2/common.h>
+#include <openrct2/config/Config.h>
+#include <openrct2/Context.h>
+#include <openrct2/core/File.h>
+#include <openrct2/core/FileScanner.h>
+#include <openrct2/core/Guard.hpp>
+#include <openrct2/core/Json.hpp>
+#include <openrct2/core/Math.hpp>
+#include <openrct2/core/Path.hpp>
+#include <openrct2/core/String.hpp>
+#include <openrct2/drawing/Drawing.h>
+#include <openrct2/localisation/Language.h>
+#include <openrct2/localisation/StringIds.h>
+#include <openrct2/PlatformEnvironment.h>
+#include <openrct2/interface/Colour.h>
+#include "Theme.h"
 #include "Window.h"
-#include "Window_internal.h"
-#include "Colour.h"
 
 using namespace OpenRCT2;
 
diff --git a/src/openrct2/interface/themes.h b/src/openrct2-ui/interface/Theme.h
similarity index 96%
rename from src/openrct2/interface/themes.h
rename to src/openrct2-ui/interface/Theme.h
index 94678c4894..eb497eb29a 100644
--- a/src/openrct2/interface/themes.h
+++ b/src/openrct2-ui/interface/Theme.h
@@ -14,11 +14,10 @@
  *****************************************************************************/
 #pragma endregion
 
-#ifndef _THEMES_H_
-#define _THEMES_H_
+#pragma once
 
-#include "../common.h"
-#include "Window.h"
+#include <openrct2/common.h>
+#include <openrct2/interface/Window.h>
 
 enum {
     UITHEME_FLAG_PREDEFINED                            = 1 << 0,
@@ -53,5 +52,3 @@ void     theme_delete();
 
 uint8         theme_desc_get_num_colours(rct_windowclass wc);
 rct_string_id theme_desc_get_name(rct_windowclass wc);
-
-#endif
diff --git a/src/openrct2-ui/interface/Window.cpp b/src/openrct2-ui/interface/Window.cpp
index 0e06671227..b758f2c1ab 100644
--- a/src/openrct2-ui/interface/Window.cpp
+++ b/src/openrct2-ui/interface/Window.cpp
@@ -1,10 +1,10 @@
 #include <openrct2/audio/audio.h>
 #include <openrct2/config/Config.h>
 #include <openrct2/Context.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/OpenRCT2.h>
 #include <openrct2/world/Sprite.h>
 #include <openrct2/ui/UiContext.h>
+#include "Theme.h"
 #include "Window.h"
 
 #define RCT2_NEW_WINDOW         (gWindowNextSlot)
diff --git a/src/openrct2-ui/windows/EditorBottomToolbar.cpp b/src/openrct2-ui/windows/EditorBottomToolbar.cpp
index 47632b01a0..2c1e1c964f 100644
--- a/src/openrct2-ui/windows/EditorBottomToolbar.cpp
+++ b/src/openrct2-ui/windows/EditorBottomToolbar.cpp
@@ -26,13 +26,13 @@
 #include <openrct2/Input.h>
 #include <openrct2/sprites.h>
 #include <openrct2/localisation/Localisation.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/windows/Intent.h>
 #include <openrct2/world/Scenery.h>
 #include <openrct2/management/Research.h>
 #include <openrct2/scenario/Scenario.h>
 #include <openrct2/world/Park.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 enum {
diff --git a/src/openrct2-ui/windows/GameBottomToolbar.cpp b/src/openrct2-ui/windows/GameBottomToolbar.cpp
index 73aece126a..57a81d423e 100644
--- a/src/openrct2-ui/windows/GameBottomToolbar.cpp
+++ b/src/openrct2-ui/windows/GameBottomToolbar.cpp
@@ -21,7 +21,6 @@
 #include <openrct2/core/Math.hpp>
 #include <openrct2/Game.h>
 #include <openrct2/Input.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/localisation/Date.h>
 #include <openrct2/localisation/Localisation.h>
@@ -33,6 +32,7 @@
 #include <openrct2/world/Park.h>
 #include <openrct2/world/Sprite.h>
 #include <openrct2/management/Finance.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 enum WINDOW_GAME_BOTTOM_TOOLBAR_WIDGET_IDX
diff --git a/src/openrct2-ui/windows/MapTooltip.cpp b/src/openrct2-ui/windows/MapTooltip.cpp
index 5165d73708..b215e3d583 100644
--- a/src/openrct2-ui/windows/MapTooltip.cpp
+++ b/src/openrct2-ui/windows/MapTooltip.cpp
@@ -18,10 +18,10 @@
 
 #include <openrct2/Context.h>
 #include <openrct2/Input.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/localisation/Localisation.h>
 #include <openrct2/drawing/Drawing.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 static rct_widget window_map_tooltip_widgets[] = {
diff --git a/src/openrct2-ui/windows/Options.cpp b/src/openrct2-ui/windows/Options.cpp
index 00f95c07a0..4fcdb9194f 100644
--- a/src/openrct2-ui/windows/Options.cpp
+++ b/src/openrct2-ui/windows/Options.cpp
@@ -34,7 +34,6 @@
 #include <openrct2-ui/windows/Window.h>
 
 #include <openrct2/audio/audio.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Viewport.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/localisation/Currency.h>
@@ -47,6 +46,7 @@
 #include <openrct2/util/Util.h>
 #include <openrct2-ui/interface/Dropdown.h>
 #include <openrct2/scenario/Scenario.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 enum WINDOW_OPTIONS_PAGE {
diff --git a/src/openrct2-ui/windows/Park.cpp b/src/openrct2-ui/windows/Park.cpp
index 4f5ac9fb39..93604aeb51 100644
--- a/src/openrct2-ui/windows/Park.cpp
+++ b/src/openrct2-ui/windows/Park.cpp
@@ -33,9 +33,9 @@
 #include <openrct2/util/Util.h>
 #include <openrct2/world/Entrance.h>
 #include <openrct2-ui/interface/Dropdown.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/world/Park.h>
 #include <openrct2/scenario/Scenario.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 enum WINDOW_PARK_PAGE {
diff --git a/src/openrct2-ui/windows/Ride.cpp b/src/openrct2-ui/windows/Ride.cpp
index 00720ec934..17f2ddbe9a 100644
--- a/src/openrct2-ui/windows/Ride.cpp
+++ b/src/openrct2-ui/windows/Ride.cpp
@@ -27,7 +27,6 @@
 #include <openrct2/core/Util.hpp>
 #include <openrct2/Game.h>
 #include <openrct2/Input.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Viewport.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/localisation/Date.h>
@@ -51,6 +50,7 @@
 #include <openrct2/ride/Station.h>
 #include <openrct2/world/Park.h>
 #include <openrct2/ride/TrackDesign.h>
+#include "../interface/Theme.h"
 
 enum {
     WINDOW_RIDE_PAGE_MAIN,
diff --git a/src/openrct2-ui/windows/RideList.cpp b/src/openrct2-ui/windows/RideList.cpp
index f609417426..039e911d44 100644
--- a/src/openrct2-ui/windows/RideList.cpp
+++ b/src/openrct2-ui/windows/RideList.cpp
@@ -20,7 +20,6 @@
 #include <openrct2/Context.h>
 #include <openrct2/core/Util.hpp>
 #include <openrct2/Game.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/localisation/Localisation.h>
 #include <openrct2/network/network.h>
@@ -30,6 +29,7 @@
 #include <openrct2/world/Park.h>
 #include <openrct2/interface/Colour.h>
 #include <openrct2/drawing/Drawing.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 enum {
diff --git a/src/openrct2-ui/windows/ServerStart.cpp b/src/openrct2-ui/windows/ServerStart.cpp
index 4e4443c2fd..80fda12de4 100644
--- a/src/openrct2-ui/windows/ServerStart.cpp
+++ b/src/openrct2-ui/windows/ServerStart.cpp
@@ -22,10 +22,10 @@
 #include <openrct2-ui/windows/Window.h>
 
 #include <openrct2/interface/Chat.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/localisation/Localisation.h>
 #include <openrct2/util/Util.h>
+#include "../interface/Theme.h"
 
 static char _port[7];
 static char _name[65];
diff --git a/src/openrct2-ui/windows/Staff.cpp b/src/openrct2-ui/windows/Staff.cpp
index c5116ccfa0..c89b4d44fe 100644
--- a/src/openrct2-ui/windows/Staff.cpp
+++ b/src/openrct2-ui/windows/Staff.cpp
@@ -29,10 +29,10 @@
 #include <openrct2/world/Footpath.h>
 #include <openrct2/Input.h>
 #include <openrct2-ui/interface/Dropdown.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/world/Sprite.h>
 #include <openrct2/world/Park.h>
 #include <openrct2/management/Finance.h>
+#include "../interface/Theme.h"
 
 #define WW 190
 #define WH 180
diff --git a/src/openrct2-ui/windows/Themes.cpp b/src/openrct2-ui/windows/Themes.cpp
index 84814da7b6..9f81762d15 100644
--- a/src/openrct2-ui/windows/Themes.cpp
+++ b/src/openrct2-ui/windows/Themes.cpp
@@ -24,9 +24,9 @@
 #include <openrct2/localisation/Localisation.h>
 #include <openrct2/sprites.h>
 #include <openrct2-ui/interface/Dropdown.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/util/Util.h>
 #include <openrct2/drawing/Drawing.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 enum {
diff --git a/src/openrct2-ui/windows/TitleCommandEditor.cpp b/src/openrct2-ui/windows/TitleCommandEditor.cpp
index efd681f8d8..ac854f00b2 100644
--- a/src/openrct2-ui/windows/TitleCommandEditor.cpp
+++ b/src/openrct2-ui/windows/TitleCommandEditor.cpp
@@ -22,7 +22,6 @@
 #include <openrct2/Game.h>
 #include <openrct2/Input.h>
 #include <openrct2/core/Util.hpp>
-#include <openrct2/interface/themes.h>
 #include <openrct2-ui/interface/Viewport.h>
 #include <openrct2-ui/interface/Widget.h>
 #include <openrct2/scenario/ScenarioRepository.h>
@@ -33,6 +32,7 @@
 #include <openrct2-ui/interface/Dropdown.h>
 #include <openrct2/world/Sprite.h>
 #include <openrct2/drawing/Drawing.h>
+#include "../interface/Theme.h"
 
 // clang-format off
 struct TITLE_COMMAND_ORDER {
diff --git a/src/openrct2-ui/windows/TitleScenarioSelect.cpp b/src/openrct2-ui/windows/TitleScenarioSelect.cpp
index 127c6588d9..a629251cde 100644
--- a/src/openrct2-ui/windows/TitleScenarioSelect.cpp
+++ b/src/openrct2-ui/windows/TitleScenarioSelect.cpp
@@ -17,7 +17,6 @@
 #include <vector>
 #include <openrct2/audio/audio.h>
 #include <openrct2/config/Config.h>
-#include <openrct2/interface/themes.h>
 #include <openrct2/localisation/Date.h>
 #include <openrct2/localisation/Localisation.h>
 #include <openrct2/localisation/LocalisationService.h>
@@ -29,6 +28,7 @@
 #include <openrct2-ui/windows/Window.h>
 #include <openrct2/drawing/Drawing.h>
 #include <openrct2/scenario/Scenario.h>
+#include "../interface/Theme.h"
 
 #define INITIAL_NUM_UNLOCKED_SCENARIOS 5