diff --git a/vehicle_gui.c b/vehicle_gui.c
index e767002419..bec8e1516d 100644
--- a/vehicle_gui.c
+++ b/vehicle_gui.c
@@ -198,7 +198,7 @@ static void BuildVehicleList(vehiclelist_d* vl, int type, PlayerID owner, Statio
 	vl->flags |= VL_RESORT;
 }
 
-void SortVehicleList(vehiclelist_d *vl)
+static void SortVehicleList(vehiclelist_d *vl)
 {
 	if (!(vl->flags & VL_RESORT)) return;
 
diff --git a/vehicle_gui.h b/vehicle_gui.h
index 103f5db9ef..1b2bc6a1a0 100644
--- a/vehicle_gui.h
+++ b/vehicle_gui.h
@@ -17,8 +17,6 @@ void InitializeVehiclesGuiList(void);
 void RebuildVehicleLists(void);
 void ResortVehicleLists(void);
 
-void SortVehicleList(struct vehiclelist_d *vl);
-
 #define PERIODIC_RESORT_DAYS 10
 #define SORT_BY_UNSORTED 0
 extern const StringID _vehicle_sort_listing[];