Index: ai/aiunit.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/ai/aiunit.c,v
retrieving revision 1.330
diff -u -r1.330 aiunit.c
--- ai/aiunit.c	29 Aug 2004 20:14:41 -0000	1.330
+++ ai/aiunit.c	29 Aug 2004 21:14:03 -0000
@@ -336,29 +336,35 @@
 {
   struct city *pcity = map_get_city(punit->x, punit->y);
   bool has_defense = FALSE;
-
-  CHECK_UNIT(punit);
+  int mydef, units = -2;
 
   if (!pcity) {
     return FALSE;
   }
+  mydef = assess_defense_unit(pcity, punit, FALSE);
 
   unit_list_iterate(map_get_tile(pcity->x, pcity->y)->units, pdef) {
-    if (assess_defense_unit(pcity, punit, FALSE) >= 0
+    if (assess_defense_unit(pcity, pdef, FALSE) >= mydef
 	&& pdef != punit
 	&& pdef->homecity == pcity->id) {
       has_defense = TRUE;
     }
+    units++;
   } unit_list_iterate_end;
  
   /* Guess I better stay / you can live at home now */
   if (!has_defense && pcity->ai.danger > 0) {
-    /* change homecity to this city */
+    /* Change homecity to this city */
     if (ai_unit_make_homecity(punit, pcity)) {
       /* Very important, or will not stay -- Syela */
       ai_unit_new_role(punit, AIUNIT_DEFEND_HOME, pcity->x, pcity->y);
       return TRUE;
-    }
+    } /* else city cannot upkeep us! */
+  }
+  /* Treat grave danger */
+  if (pcity->ai.grave_danger > units) {
+    ai_unit_new_role(punit, AIUNIT_DEFEND_HOME, pcity->x, pcity->y);
+    return TRUE;
   }
   return FALSE;
 }