diff --git a/doc/fixes36.3 b/doc/fixes36.3
index bf389167d..82ada4627 100644
--- a/doc/fixes36.3
+++ b/doc/fixes36.3
@@ -42,6 +42,8 @@ some improvement to the handling of endgame levels filling up with monsters
 
 Fixes to Post-3.6.2 Problems that Were Exposed Via git Repository
 ------------------------------------------------------------------
+elemental_clog() loop needed to guard against obliteration of the monster
+	that was trying to be placed
 curses: sometimes the message window would show a blank line after a prompt
 
 
diff --git a/src/dungeon.c b/src/dungeon.c
index eff67af3a..8cf395abe 100644
--- a/src/dungeon.c
+++ b/src/dungeon.c
@@ -1,4 +1,4 @@
-/* NetHack 3.6	dungeon.c	$NHDT-Date: 1558853012 2019/05/26 06:43:32 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.94 $ */
+/* NetHack 3.6	dungeon.c	$NHDT-Date: 1559476918 2019/06/02 12:01:58 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.95 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Robert Patrick Rankin, 2012. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -1185,6 +1185,13 @@ void
 u_on_newpos(x, y)
 int x, y;
 {
+    if (!isok(x, y)) { /* validate location */
+        void VDECL((*func), (const char *, ...)) PRINTF_F(1, 2);
+
+        func = (x < 0 || y < 0 || x > COLNO - 1 || y > ROWNO - 1) ? panic
+               : impossible;
+        (*func)("u_on_newpos: trying to place hero off map <%d,%d>", x, y);
+    }
     u.ux = x;
     u.uy = y;
 #ifdef CLIPPING
diff --git a/src/mkobj.c b/src/mkobj.c
index eb949d9a9..7501158f8 100644
--- a/src/mkobj.c
+++ b/src/mkobj.c
@@ -1,4 +1,4 @@
-/* NetHack 3.6	mkobj.c	$NHDT-Date: 1558124913 2019/05/17 20:28:33 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.147 $ */
+/* NetHack 3.6	mkobj.c	$NHDT-Date: 1559476922 2019/06/02 12:02:02 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.149 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Derek S. Ray, 2015. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -1723,8 +1723,17 @@ int x, y;
 {
     register struct obj *otmp2 = g.level.objects[x][y];
 
+    if (!isok(x, y)) { /* validate location */
+        void VDECL((*func), (const char *, ...)) PRINTF_F(1, 2);
+
+        func = (x < 0 || y < 0 || x > COLNO - 1 || y > ROWNO - 1) ? panic
+               : impossible;
+        (*func)("place_object: \"%s\" [%d] off map <%d,%d>",
+                safe_typename(otmp->otyp), otmp->where, x, y);
+    }
     if (otmp->where != OBJ_FREE)
-        panic("place_object: obj not free");
+        panic("place_object: obj \"%s\" [%d] not free",
+              safe_typename(otmp->otyp), otmp->where);
 
     obj_no_longer_held(otmp);
     if (otmp->otyp == BOULDER) {
diff --git a/src/mon.c b/src/mon.c
index f76f67eee..a385eb7a4 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -1845,10 +1845,9 @@ struct permonst *mptr; /* reflects mtmp->data _prior_ to mtmp's death */
         shkgone(mtmp);
     if (mtmp->wormno)
         wormgone(mtmp);
-    if (In_endgame(&u.uz)) {
-        mtmp->mx = mtmp->my = 0;
+    if (In_endgame(&u.uz))
         mtmp->mstate |= MON_ENDGAME_FREE;
-    }
+
     mtmp->mstate |= MON_DETACH;
     iflags.purge_monsters++;
 }
@@ -2633,7 +2632,7 @@ struct monst *mon;
         m1 = m2 = m3 = m4 = m5 = zm = (struct monst *) 0;
         if (!msgmv || (g.moves - msgmv) > 200L) {
             if (!msgmv || rn2(2))
-                You("feel besieged.");
+                You_feel("besieged.");
             msgmv = g.moves;
         }
         /*
@@ -2644,7 +2643,7 @@ struct monst *mon;
          * m5 a pet.
          */
         for (mtmp = fmon; mtmp; mtmp = mtmp->nmon) {
-            if (DEADMONSTER(mtmp))
+            if (DEADMONSTER(mtmp) || mtmp == mon)
                 continue;
             if (mtmp->mx == 0 && mtmp->my == 0)
                 continue;
@@ -2679,8 +2678,9 @@ struct monst *mon;
 
             mtmp->mstate |= MON_OBLITERATE;
             mongone(mtmp);
-            mtmp->mx = mtmp->my = 0;
-            rloc_to(mon, mx, my);
+            /* some places in the code might still reference mtmp->mx, mtmp->my */
+            /* mtmp->mx = mtmp->my = 0; */ 
+            rloc_to(mon, mx, my);           /* note: mon, not mtmp */
         } else {
             /* last resort - migrate mon to the next plane */
             if (Is_waterlevel(&u.uz) || Is_firelevel(&u.uz) || Is_earthlevel(&u.uz)) {