diff --git a/src/openrct2-ui/interface/Dropdown.h b/src/openrct2-ui/interface/Dropdown.h
index 39e19cc7e1..4d232483d7 100644
--- a/src/openrct2-ui/interface/Dropdown.h
+++ b/src/openrct2-ui/interface/Dropdown.h
@@ -54,8 +54,6 @@ namespace OpenRCT2::Ui::Windows
     void WindowDropdownShowColour(
         WindowBase* w, Widget* widget, ColourWithFlags dropdownColour, colour_t selectedColour,
         bool alwaysHideSpecialColours = false);
-    void WindowDropdownShowColourAvailable(
-        WindowBase* w, Widget* widget, uint8_t dropdownColour, uint8_t selectedColour, uint32_t availableColours);
 
     colour_t ColourDropDownIndexToColour(uint8_t ddidx);