diff --git a/newgrf.c b/newgrf.c
--- a/newgrf.c
+++ b/newgrf.c
@@ -1761,9 +1761,11 @@ static void VehicleNewName(byte *buf, in
 				case GSF_TRAIN:
 				case GSF_ROAD:
 				case GSF_SHIP:
-				case GSF_AIRCRAFT:
-					SetCustomEngineName(id, AddGRFString(_cur_grffile->grfid, id, lang, name));
+				case GSF_AIRCRAFT: {
+					StringID string = AddGRFString(_cur_grffile->grfid, id, lang, name);
+					if (id < TOTAL_NUM_ENGINES) SetCustomEngineName(id, string);
 					break;
+				}
 
 #if 0
 				case GSF_STATION: