diff --git a/src/common/gamecode/economy.c b/src/common/gamecode/economy.c
index 215a65648..3c4a00780 100644
--- a/src/common/gamecode/economy.c
+++ b/src/common/gamecode/economy.c
@@ -973,6 +973,7 @@ maintain(building * b, boolean first)
 	return true;
 }
 
+#ifdef COLLAPSE_CHANCE
 static void
 gebaeude_stuerzt_ein(region * r, building * b)
 {
@@ -990,11 +991,13 @@ gebaeude_stuerzt_ein(region * r, building * b)
       freset(u, UFL_OWNER);
       leave(r,u);
       n = u->number;
+#ifdef COLLAPSE_SURVIVAL
       for (i = 0; i < n; i++) {
         if (rng_double() >= COLLAPSE_SURVIVAL) {
           ++loss;
         }
       }
+#endif
       scale_number(u, u->number - loss);
       opfer += loss;
     }
@@ -1012,6 +1015,7 @@ gebaeude_stuerzt_ein(region * r, building * b)
   msg_release(msg);
   remove_building(&r->buildings, b);
 }
+#endif
 
 void
 maintain_buildings(region * r, boolean crash)
@@ -1023,10 +1027,13 @@ maintain_buildings(region * r, boolean crash)
 
     /* the second time, send a message */
     if (crash) {
+#ifdef COLLAPSE_CHANCE
       if (!maintained && (rng_double() < COLLAPSE_CHANCE)) {
         gebaeude_stuerzt_ein(r, b);
         continue;
-      } else if (!fval(b, BLD_WORKING)) {
+      }
+#endif
+      if (!fval(b, BLD_WORKING)) {
         unit * u = buildingowner(r, b);
         const char * msgtype = maintained?"maintenance_nowork":"maintenance_none";
         struct message * msg = msg_message(msgtype, "building", b);
diff --git a/src/common/kernel/eressea.h b/src/common/kernel/eressea.h
index 0b93b9146..21a27bbe5 100644
--- a/src/common/kernel/eressea.h
+++ b/src/common/kernel/eressea.h
@@ -66,13 +66,15 @@ extern "C" {
 #define PLAGUE_HEALCHANCE  0.25F /* Wahrscheinlichkeit Heilung */
 #define PLAGUE_HEALCOST    30    /* Heilkosten */
 
-/** Monster */
+/* Chance of a monster attack */
+#define MONSTERATTACK  0.4F
 
-#define MONSTERATTACK  0.4F /* Chance für Monsterangriff */
-
-/** Gebäude */
-#define COLLAPSE_CHANCE    0.4F /* Chance für Einsturz bei unversorgtem Gebaeude */
-#define COLLAPSE_SURVIVAL  0.5F /* Soviele % überleben den Einsturz */
+/** Chance of an unmaintained building crashing */
+/* #define COLLAPSE_CHANCE 0.4F */
+#undef COLLAPSE_CHANCE
+/** chance to survive the crash of a building */
+/* #define COLLAPSE_SURVIVAL 0.5F */
+#undef COLLAPSE_SURVIVAL
 
 /* Magiesystem */
 #define NIGHT_EYE_TALENT        5
diff --git a/src/eressea/lua/building.cpp b/src/eressea/lua/building.cpp
index fff9a9e6d..87977c84b 100644
--- a/src/eressea/lua/building.cpp
+++ b/src/eressea/lua/building.cpp
@@ -56,9 +56,9 @@ lc_age(struct attrib * a)
       try {
         if (fparam) {
           std::string param(fparam);
-          retval = luabind::call_function<int>(L, fname, *b, param);
+          retval = luabind::call_function<int>(L, fname, b, param);
         } else {
-          retval = luabind::call_function<int>(L, fname, *b);
+          retval = luabind::call_function<int>(L, fname, b);
         }
       }
       catch (luabind::error& e) {
@@ -166,10 +166,10 @@ public:
 
 
 static eressea::list<unit *, unit *, buildingunit>
-building_units(const building& b) {
-  region * r = b.region;
+building_units(const building * b) {
+  region * r = b->region;
   unit * u = r->units;
-  while (u!=NULL && (!u->building || u->building->no!=b.no)) u=u->next;
+  while (u!=NULL && (!u->building || u->building->no!=b->no)) u=u->next;
   return eressea::list<unit *, unit *, buildingunit>(u);
 }
 
diff --git a/src/eressea/lua/unit.cpp b/src/eressea/lua/unit.cpp
index ce7b4995e..73eda48f1 100644
--- a/src/eressea/lua/unit.cpp
+++ b/src/eressea/lua/unit.cpp
@@ -317,9 +317,9 @@ unit_hpmax(const unit& u)
 }
 
 static void
-unit_setregion(unit& u, region& r)
+unit_setregion(unit * u, region * r)
 {
-  move_unit(&u, &r, NULL);
+  move_unit(u, r, NULL);
 }
 
 static region *
@@ -329,13 +329,13 @@ unit_getregion(const unit& u)
 }
 
 static void
-unit_setship(unit& u, ship& s)
+unit_setship(unit& u, const ship& s)
 {
   leave(u.region, &u);
   if (u.region!=s.region) {
-    unit_setregion(u, *s.region);
+    move_unit(&u, s.region, NULL);
   }
-  u.ship = &s;
+  u.ship = findship(s.no);
 }
 
 static ship *
@@ -345,13 +345,14 @@ unit_getship(const unit& u)
 }
 
 static void
-unit_setbuilding(unit& u, building& b)
+unit_setbuilding(unit * u, building * b)
 {
-  leave(u.region, &u);
-  if (u.region!=b.region) {
-    unit_setregion(u, *b.region);
+  leave(u->region, u);
+  if (u->region!=b->region) {
+    move_unit(u, b->region, NULL);
   }
-  u.building = &b;
+  assert(b==findbuilding(b->no));
+  u->building = b;
 }
 
 static building *