diff --git a/src/hack.c b/src/hack.c
index d9c87000f..a689aa9a1 100644
--- a/src/hack.c
+++ b/src/hack.c
@@ -173,7 +173,6 @@ moverock()
 		    if (rn2(10)) {
 			obj_extract_self(otmp);
 			place_object(otmp, rx, ry);
-			unblock_point(sx, sy);
 			newsym(sx, sy);
 			pline("KAABLAMM!!!  %s %s land mine.",
 			      Tobjnam(otmp, "trigger"),
diff --git a/src/mon.c b/src/mon.c
index 0dc07c45e..c220429c6 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -886,10 +886,7 @@ mpickstuff(mtmp, str)
 			pline("%s picks up %s.", Monnam(mtmp),
 			      (distu(mtmp->mx, mtmp->my) <= 5) ?
 				doname(otmp) : distant_name(otmp, doname));
-		obj_extract_self(otmp);
-		/* unblock point after extract, before pickup */
-		if (otmp->otyp == BOULDER)
-		    unblock_point(otmp->ox,otmp->oy);	/* vision */
+		obj_extract_self(otmp);		/* remove from floor */
 		(void) mpickobj(mtmp, otmp);	/* may merge and free otmp */
 		m_dowear(mtmp, FALSE);
 		newsym(mtmp->mx, mtmp->my);
diff --git a/src/zap.c b/src/zap.c
index d187e01cb..fc2b73ba2 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -1455,13 +1455,6 @@ poly_obj(obj, id)
 	otmp->owornmask = obj->owornmask;
 no_unwear:
 
-	if (obj_location == OBJ_FLOOR && obj->otyp == BOULDER &&
-		otmp->otyp != BOULDER)
-	    unblock_point(obj->ox, obj->oy);
-	else if (obj_location == OBJ_FLOOR && obj->otyp != BOULDER &&
-		otmp->otyp == BOULDER)
-	    block_point(obj->ox, obj->oy);
-
 	/* ** we are now done adjusting the object ** */
 
 
@@ -1477,6 +1470,14 @@ no_unwear:
 	    freeinv_core(obj);
 	    addinv_core1(otmp);
 	    addinv_core2(otmp);
+	} else if (obj_location == OBJ_FLOOR) {
+	    ox = otmp->ox,  oy = otmp->oy;	/* set by replace_object() */
+	    if (obj->otyp == BOULDER && otmp->otyp != BOULDER &&
+		    !does_block(ox, oy, &levl[ox][oy]))
+		unblock_point(ox, oy);
+	    else if (obj->otyp != BOULDER && otmp->otyp == BOULDER)
+		    /* (checking does_block() here would be redundant) */
+		block_point(ox, oy);
 	}
 
 	if ((!carried(otmp) || obj->unpaid) &&