diff --git a/src/rail_gui.cpp b/src/rail_gui.cpp
index ca20a66ca1..0ee62cc01f 100644
--- a/src/rail_gui.cpp
+++ b/src/rail_gui.cpp
@@ -35,6 +35,7 @@
 #include "vehicle_func.h"
 #include "zoom_func.h"
 #include "rail_gui.h"
+#include "toolbar_gui.h"
 #include "station_cmd.h"
 #include "tunnelbridge_cmd.h"
 #include "waypoint_cmd.h"
@@ -838,7 +839,6 @@ struct BuildRailToolbarWindow : Window {
 	static EventState RailToolbarGlobalHotkeys(int hotkey)
 	{
 		if (_game_mode != GM_NORMAL) return ES_NOT_HANDLED;
-		extern RailType _last_built_railtype;
 		Window *w = ShowBuildRailToolbar(_last_built_railtype);
 		if (w == nullptr) return ES_NOT_HANDLED;
 		return w->OnHotkey(hotkey);
@@ -1929,7 +1929,6 @@ void InitializeRailGui()
  */
 void ReinitGuiAfterToggleElrail(bool disable)
 {
-	extern RailType _last_built_railtype;
 	if (disable && _last_built_railtype == RAILTYPE_ELECTRIC) {
 		_last_built_railtype = _cur_railtype = RAILTYPE_RAIL;
 		BuildRailToolbarWindow *w = dynamic_cast<BuildRailToolbarWindow *>(FindWindowById(WC_BUILD_TOOLBAR, TRANSPORT_RAIL));
@@ -1943,7 +1942,6 @@ static void SetDefaultRailGui()
 {
 	if (_local_company == COMPANY_SPECTATOR || !Company::IsValidID(_local_company)) return;
 
-	extern RailType _last_built_railtype;
 	RailType rt;
 	switch (_settings_client.gui.default_rail_type) {
 		case 2: {
diff --git a/src/road_gui.cpp b/src/road_gui.cpp
index 475be95796..42fc2e08a9 100644
--- a/src/road_gui.cpp
+++ b/src/road_gui.cpp
@@ -27,6 +27,7 @@
 #include "company_base.h"
 #include "hotkeys.h"
 #include "road_gui.h"
+#include "toolbar_gui.h"
 #include "zoom_func.h"
 #include "dropdown_type.h"
 #include "dropdown_func.h"
@@ -862,13 +863,11 @@ struct BuildRoadToolbarWindow : Window {
 
 	static EventState RoadToolbarGlobalHotkeys(int hotkey)
 	{
-		extern RoadType _last_built_roadtype;
 		return RoadTramToolbarGlobalHotkeys(hotkey, _last_built_roadtype, RTT_ROAD);
 	}
 
 	static EventState TramToolbarGlobalHotkeys(int hotkey)
 	{
-		extern RoadType _last_built_tramtype;
 		return RoadTramToolbarGlobalHotkeys(hotkey, _last_built_tramtype, RTT_TRAM);
 	}
 
diff --git a/src/toolbar_gui.h b/src/toolbar_gui.h
index 40d7f282cd..fdf941fbbe 100644
--- a/src/toolbar_gui.h
+++ b/src/toolbar_gui.h
@@ -10,6 +10,9 @@
 #ifndef TOOLBAR_GUI_H
 #define TOOLBAR_GUI_H
 
+#include "rail_type.h"
+#include "road_type.h"
+
 enum MainToolbarHotkeys : int32_t {
 	MTHK_PAUSE,
 	MTHK_FASTFORWARD,
@@ -60,4 +63,8 @@ void ToggleWidgetOutlines();
 
 extern uint _toolbar_width;
 
+extern RailType _last_built_railtype; ///< The most recently used type of rail.
+extern RoadType _last_built_roadtype; ///< The most recently used type of road.
+extern RoadType _last_built_tramtype; ///< The most recently used type of tram track.
+
 #endif /* TOOLBAR_GUI_H */