1 files changed, 1 insertions, 0 deletions
diff --git a/src/vehicle.h b/src/vehicle.h
index cb0025a9d..9a14c66f7 100644
--- a/src/vehicle.h
+++ b/src/vehicle.h
@@ -429,6 +429,7 @@ static inline bool IsPlayerBuildableVehicleType(const Vehicle *v)
  */
 static inline byte VehTypeToIndex(byte type)
 {
+	assert(IsPlayerBuildableVehicleType(type));
 	return type - VEH_Train;
 }