diff --git a/src/monmove.c b/src/monmove.c
index a21716e06..15e7752c7 100644
--- a/src/monmove.c
+++ b/src/monmove.c
@@ -1511,6 +1511,8 @@ postmov(
             if (mtmp->mx)
                 newsym(mtmp->mx, mtmp->my);
             return MMOVE_DIED; /* it died */
+        } else if (mon_offmap(mtmp)) {
+            return MMOVE_DONE;
         }
         ptr = mtmp->data; /* in case mintrap() caused polymorph */
 
diff --git a/src/teleport.c b/src/teleport.c
index fc1d3ce28..affa19007 100644
--- a/src/teleport.c
+++ b/src/teleport.c
@@ -2139,9 +2139,10 @@ rloco(struct obj *obj)
                                            svd.dndest.nhx, svd.dndest.nhy)));
 
     if (flooreffects(obj, tx, ty, "fall")) {
-        /* update old location since flooreffects() couldn't;
+        /* update old location (if any) since flooreffects() couldn't;
            unblock_point() for boulder handled by obj_extract_self() */
-        newsym(otx, oty);
+        if (!(otx == 0 && oty == 0))
+            newsym(otx, oty);
         return FALSE;
     } else if (otx == 0 && oty == 0) {
         ; /* fell through a trap door; no update of old loc needed */
diff --git a/src/trap.c b/src/trap.c
index 8b40d3faf..5d81dec5d 100644
--- a/src/trap.c
+++ b/src/trap.c
@@ -2698,9 +2698,6 @@ trapeffect_rolling_boulder_trap(
                     trap->tseen = TRUE;
                 if (DEADMONSTER(mtmp))
                     trapkilled = TRUE;
-            } else {
-                deltrap(trap);
-                newsym(mtmp->mx, mtmp->my);
             }
             return trapkilled ? Trap_Killed_Mon : mtmp->mtrapped
                 ? Trap_Caught_Mon : Trap_Effect_Finished;