diff --git a/src/common/gamecode/creport.c b/src/common/gamecode/creport.c
index 04000bbac..aa83b6ad3 100644
--- a/src/common/gamecode/creport.c
+++ b/src/common/gamecode/creport.c
@@ -678,7 +678,7 @@ cr_output_unit(FILE * F, const region * r,
     itemcloak = curse_active(get_curse(u->attribs, itemcloak_ct));
   }
 
-  assert(u);
+  assert(u && u->number);
 
 #if KARMA_MODULE
   if (fspecial(u->faction, FS_HIDDEN))
diff --git a/src/common/kernel/building.c b/src/common/kernel/building.c
index 4f971ee2f..7278a33d9 100644
--- a/src/common/kernel/building.c
+++ b/src/common/kernel/building.c
@@ -374,7 +374,7 @@ register_buildings(void)
 void
 write_building_reference(const struct building * b, struct storage * store)
 {
-  store->w_id(store, b?b->no:0);
+  store->w_id(store, (b && b->region)?b->no:0);
 }
 
 
diff --git a/src/common/kernel/curse.h b/src/common/kernel/curse.h
index 7e571afc3..5fd40385f 100644
--- a/src/common/kernel/curse.h
+++ b/src/common/kernel/curse.h
@@ -292,7 +292,6 @@ extern struct curse * get_curse(struct attrib *ap, const curse_type * ctype);
    * oder einen NULL-pointer
    * */
 
-struct unit * get_tracingunit(struct attrib **ap, const curse_type * ct);
 int find_cursebyname(const char *c);
 const curse_type * ct_find(const char *c);
 void ct_register(const curse_type *);
diff --git a/src/common/kernel/magic.c b/src/common/kernel/magic.c
index 820a730de..31d17a6e5 100644
--- a/src/common/kernel/magic.c
+++ b/src/common/kernel/magic.c
@@ -2108,7 +2108,7 @@ sm_familiar(const unit * u, const region * r, skill_t sk, int value) /* skillmod
     int mod;
     unit * familiar = get_familiar(u);
     if (familiar==NULL) {
-      log_error(("[sm_familiar] %s has a familiar-skillmod, but no familiar\n", unitname(u)));
+      /* the familiar is dead */
       return value;
     }
     mod = eff_skill(familiar, sk, r)/2;
@@ -2391,16 +2391,22 @@ attrib_type at_clone = {
 unit *
 get_familiar(const unit *u)
 {
-	attrib * a = a_find(u->attribs, &at_familiar);
-	if (a!=NULL) return (unit*)a->data.v;
-	return NULL;
+  attrib * a = a_find(u->attribs, &at_familiar);
+  if (a!=NULL) {
+    unit * u = (unit*)a->data.v;
+    if (u->number>0) return u;
+  }
+  return NULL;
 }
 
 unit *
 get_familiar_mage(const unit *u)
 {
 	attrib * a = a_find(u->attribs, &at_familiarmage);
-	if (a!=NULL) return (unit*)a->data.v;
+    if (a!=NULL) {
+      unit * u = (unit*)a->data.v;
+      if (u->number>0) return u;
+    }
 	return NULL;
 }
 
@@ -2408,7 +2414,10 @@ unit *
 get_clone(const unit *u)
 {
 	attrib * a = a_find(u->attribs, &at_clone);
-	if (a!=NULL) return (unit*)a->data.v;
+    if (a!=NULL) {
+      unit * u = (unit*)a->data.v;
+      if (u->number>0) return u;
+    }
 	return NULL;
 }
 
@@ -2416,7 +2425,10 @@ unit *
 get_clone_mage(const unit *u)
 {
   attrib * a = a_find(u->attribs, &at_clonemage);
-  if (a!=NULL) return (unit*)a->data.v;
+  if (a!=NULL) {
+    unit * u = (unit*)a->data.v;
+    if (u->number>0) return u;
+  }
   return NULL;
 }
 
diff --git a/src/common/kernel/ship.c b/src/common/kernel/ship.c
index 950b0b2cf..31991d461 100644
--- a/src/common/kernel/ship.c
+++ b/src/common/kernel/ship.c
@@ -307,7 +307,7 @@ shipowner(const ship * sh)
 void
 write_ship_reference(const struct ship * sh, struct storage * store)
 {
-  store->w_id(store, sh?sh->no:0);
+  store->w_id(store, (sh && sh->region)?sh->no:0);
 }
 
 void
diff --git a/src/common/kernel/unit.c b/src/common/kernel/unit.c
index d72b262c6..5b96829b2 100644
--- a/src/common/kernel/unit.c
+++ b/src/common/kernel/unit.c
@@ -624,7 +624,7 @@ free_units(void)
 void
 write_unit_reference(const unit * u, struct storage * store)
 {
-  store->w_id(store, u?u->no:0);
+  store->w_id(store, (u && u->region)?u->no:0);
 }
 
 int