diff --git a/src/openrct2-ui/interface/Theme.cpp b/src/openrct2-ui/interface/Theme.cpp
index ecf6ae169f..df577ffb69 100644
--- a/src/openrct2-ui/interface/Theme.cpp
+++ b/src/openrct2-ui/interface/Theme.cpp
@@ -770,6 +770,55 @@ void ThemeSetColour(WindowClass wc, uint8_t index, colour_t colour)
     ThemeSave();
 }
 
+// Quick and dirty mapping for new colors to original colors, until flags are extracted from color upper bits
+colour_t ThemeOverrideExtendedColour(colour_t inputColour)
+{
+    switch (inputColour - COLOUR_ID_G2_OFFSET)
+    {
+        case COLOUR_DARK_OLIVE_DARK:
+        case COLOUR_DARK_OLIVE_LIGHT:
+            return COLOUR_DARK_OLIVE_GREEN;
+        case COLOUR_SATURATED_BROWN_LIGHT:
+            return COLOUR_LIGHT_BROWN;
+        case COLOUR_BORDEAUX_RED_DARK:
+        case COLOUR_BORDEAUX_RED_LIGHT:
+            return COLOUR_BORDEAUX_RED;
+        case COLOUR_GRASS_GREEN_DARK:
+        case COLOUR_GRASS_GREEN_LIGHT:
+            return COLOUR_MOSS_GREEN;
+        case COLOUR_OLIVE_DARK:
+        case COLOUR_OLIVE_LIGHT:
+            return COLOUR_OLIVE_GREEN;
+        case COLOUR_SATURATED_GREEN_LIGHT:
+            return COLOUR_BRIGHT_GREEN;
+        case COLOUR_TAN_DARK:
+        case COLOUR_TAN_LIGHT:
+            return COLOUR_SALMON_PINK;
+        case COLOUR_DULL_PURPLE_LIGHT:
+            return COLOUR_LIGHT_PURPLE;
+        case COLOUR_DULL_GREEN_DARK:
+        case COLOUR_DULL_GREEN_LIGHT:
+            return COLOUR_DARK_GREEN;
+        case COLOUR_SATURATED_PURPLE_DARK:
+        case COLOUR_SATURATED_PURPLE_LIGHT:
+            return COLOUR_BRIGHT_PURPLE;
+        case COLOUR_ORANGE_LIGHT:
+            return COLOUR_LIGHT_ORANGE;
+        case COLOUR_AQUA_DARK:
+            return COLOUR_AQUAMARINE;
+        case COLOUR_MAGENTA_LIGHT:
+            return COLOUR_BRIGHT_PINK;
+        case COLOUR_DULL_BROWN_DARK:
+        case COLOUR_DULL_BROWN_LIGHT:
+            return COLOUR_DARK_BROWN;
+        case COLOUR_INVISIBLE:
+        case COLOUR_VOID:
+            return COLOUR_BLACK;
+        default:
+            return inputColour;
+    }
+}
+
 uint8_t ThemeGetFlags()
 {
     return ThemeManager::CurrentTheme->Flags;
diff --git a/src/openrct2-ui/interface/Theme.h b/src/openrct2-ui/interface/Theme.h
index e0def3382d..20babae241 100644
--- a/src/openrct2-ui/interface/Theme.h
+++ b/src/openrct2-ui/interface/Theme.h
@@ -37,6 +37,7 @@ size_t ThemeGetIndexForName(const utf8* name);
 
 colour_t ThemeGetColour(WindowClass wc, uint8_t index);
 void ThemeSetColour(WindowClass wc, uint8_t index, colour_t colour);
+colour_t ThemeOverrideExtendedColour(colour_t inputColour);
 uint8_t ThemeGetFlags();
 void ThemeSetFlags(uint8_t flags);
 void ThemeSave();
diff --git a/src/openrct2-ui/windows/Themes.cpp b/src/openrct2-ui/windows/Themes.cpp
index db06190513..8eb72964f9 100644
--- a/src/openrct2-ui/windows/Themes.cpp
+++ b/src/openrct2-ui/windows/Themes.cpp
@@ -615,9 +615,10 @@ public:
             case WIDX_THEMES_LIST:
                 if (selectedIndex != -1)
                 {
+                    const auto newColour = ThemeOverrideExtendedColour(selectedIndex);
                     WindowClass wc = GetWindowClassTabIndex(_colour_index_1);
                     uint8_t colour = ThemeGetColour(wc, _colour_index_2);
-                    colour = (colour & COLOUR_FLAG_TRANSLUCENT) | selectedIndex;
+                    colour = (colour & COLOUR_FLAG_TRANSLUCENT) | newColour;
                     ThemeSetColour(wc, _colour_index_2, colour);
                     ColourSchemeUpdateAll();
                     WindowInvalidateAll();
diff --git a/src/openrct2/interface/Colour.cpp b/src/openrct2/interface/Colour.cpp
index d9ccaedecb..db80e464de 100644
--- a/src/openrct2/interface/Colour.cpp
+++ b/src/openrct2/interface/Colour.cpp
@@ -42,7 +42,6 @@ void ColoursInitMaps()
         // Get palette index in g1 / g2
         const auto paletteIndex = (i < COLOUR_NUM_ORIGINAL) ? SPR_PALETTE_2_START : SPR_G2_PALETTE_BEGIN - COLOUR_NUM_ORIGINAL;
         const G1Element* g1 = GfxGetG1Element(paletteIndex + i);
-        //TODO: Integrate themes with G2 palettes
         if (g1 != nullptr)
         {
             ColourMapA[i].colour_0 = g1->offset[INDEX_COLOUR_0];
diff --git a/src/openrct2/interface/Colour.h b/src/openrct2/interface/Colour.h
index 934cdc8d3a..7c259691bb 100644
--- a/src/openrct2/interface/Colour.h
+++ b/src/openrct2/interface/Colour.h
@@ -205,6 +205,7 @@ constexpr uint8_t PALETTE_LENGTH_ANIMATED = 16;
 
 constexpr uint8_t COLOUR_NUM_ORIGINAL = 32;
 constexpr uint8_t COLOUR_NUM_NORMAL = 54;
+// COLOUR_ID_G2_OFFSET = PALETTE_TO_G1_OFFSET_COUNT - COLOUR_NUM_ORIGINAL
 constexpr uint8_t COLOUR_ID_G2_OFFSET = 112;
 constexpr uint8_t COLOUR_OFFSET_INVISIBLE = 166;