diff --git a/src/kernel/building.c b/src/kernel/building.c
index a234f55a6..7ffba178e 100644
--- a/src/kernel/building.c
+++ b/src/kernel/building.c
@@ -95,6 +95,7 @@ void bt_register(building_type * type)
 void free_buildingtype(void *ptr) {
     building_type *btype = (building_type *)ptr;
     free_construction(btype->construction);
+    free_construction(btype->maintenance);
     free(btype->_name);
     free(btype);
 }