diff --git a/dat/Arc-loca.lua b/dat/Arc-loca.lua
index 2336a7c6f3..9a335f5542 100644
--- a/dat/Arc-loca.lua
+++ b/dat/Arc-loca.lua
@@ -33,6 +33,9 @@ local outside = selection.floodfill(00,00)
 local inside = outside:clone():negate():filter_mapchar('.')
 des.region(outside, "lit")
 
+-- Ceilings
+des.add_ceiling(inside:clone():grow() | selection.area(70,13, 76,19))
+
 -- Non diggable walls (but leave all trees diggable)
 local nondig = selection.area(00,00,75,19) ~ selection.area(00,00,50,19):filter_mapchar('T')
 des.non_diggable(nondig)
diff --git a/dat/Arc-strt.lua b/dat/Arc-strt.lua
index abc4814c72..633346fad9 100644
--- a/dat/Arc-strt.lua
+++ b/dat/Arc-strt.lua
@@ -37,6 +37,11 @@ des.map([[
 ]]);
 -- Dungeon Description
 des.region(selection.area(00,00,76,19), "lit")
+-- Ceilings
+local exterior = selection.area(00,00, 76,19):filter_mapchar(',') | selection.floodfill(02,06, true)
+                  | selection.area(71,15, 76,19) | selection.area(34,12, 41,14)
+local interior = exterior:clone():negate():filter_mapchar('.'):grow()
+des.add_ceiling(interior)
 -- Stairs
 des.stair("down",76,05)
 -- Portal arrival point
diff --git a/dat/Bar-goal.lua b/dat/Bar-goal.lua
index 8c7c58e9d8..7b6ba80c22 100644
--- a/dat/Bar-goal.lua
+++ b/dat/Bar-goal.lua
@@ -41,6 +41,11 @@ des.teleport_region({ region = {00,00,75,19}, exclude = {06,00,75,19}, dir="down
 -- and active at the same time.
 des.teleport_region({ region = {00,00,75,19}, exclude = {41,00,75,19}, dir="up" })
 
+-- Ceilings
+local exterior = selection.floodfill(00,00) + selection.floodfill(57,08)
+local covered = exterior:clone():negate():filter_mapchar('.'):grow()
+des.add_ceiling(covered)
+
 -- Stair
 local leftedge = selection.line(00,00, 00,19)
 des.stair("up", leftedge:rndcoord(1))
diff --git a/dat/Bar-loca.lua b/dat/Bar-loca.lua
index 82a855e679..4833a458ac 100644
--- a/dat/Bar-loca.lua
+++ b/dat/Bar-loca.lua
@@ -37,6 +37,11 @@ des.region(selection.area(35,14,37,15), "unlit")
 des.region(selection.area(39,03,54,08), "lit")
 des.region(selection.area(56,00,75,08), "unlit")
 des.region(selection.area(64,09,75,16), "unlit")
+-- Ceilings
+local covered = selection.floodfill(00,00, true):negate():filter_mapchar('.')
+-- only needed if the caves to the right should actually be uncovered:
+-- covered = covered - selection.floodfill(66,05)
+des.add_ceiling(covered:grow())
 -- Doors
 des.door("open",23,03)
 des.door("open",30,08)
diff --git a/dat/Bar-strt.lua b/dat/Bar-strt.lua
index 5bc69348b2..1b688fdf3e 100644
--- a/dat/Bar-strt.lua
+++ b/dat/Bar-strt.lua
@@ -55,6 +55,9 @@ des.region(selection.area(26,10,28,11), "lit")
 des.region(selection.area(04,13,06,14), "lit")
 des.region(selection.area(15,13,17,14), "lit")
 des.region(selection.area(22,14,24,15), "lit")
+-- Ceilings
+local covered = selection.floodfill(00,00):negate():filter_mapchar('.'):grow()
+des.add_ceiling(covered)
 -- Stairs
 des.stair("down", 09,09)
 -- Portal arrival point
diff --git a/dat/Hea-loca.lua b/dat/Hea-loca.lua
index 5f6373944a..44eac910ab 100644
--- a/dat/Hea-loca.lua
+++ b/dat/Hea-loca.lua
@@ -24,6 +24,8 @@ PPPPPPPPPPP........PPPPPPPPPPPP
 -- Dungeon Description
 des.region(selection.area(00,00,30,09), "lit")
 des.region({ region={12,03, 20,06}, lit=1, type="temple", filled=1 })
+-- Ceilings
+des.add_ceiling(selection.area(09,02, 21,07))
 -- Doors
 des.door("closed",09,04)
 des.door("closed",09,05)
diff --git a/dat/Hea-strt.lua b/dat/Hea-strt.lua
index 6c25b1841f..02373b73d5 100644
--- a/dat/Hea-strt.lua
+++ b/dat/Hea-strt.lua
@@ -40,6 +40,8 @@ des.replace_terrain({ region={01,01, 74,18}, fromterrain="P", toterrain=".", cha
 
 -- Dungeon Description
 des.region(selection.area(00,00,75,19), "lit")
+-- Ceilings
+des.add_ceiling(selection.area(24,07, 50,13))
 -- Stairs
 des.stair("down", 37,9)
 -- Portal arrival point
diff --git a/dat/Kni-strt.lua b/dat/Kni-strt.lua
index 59fca9303a..3f31973b6b 100644
--- a/dat/Kni-strt.lua
+++ b/dat/Kni-strt.lua
@@ -40,6 +40,9 @@ des.region({ region={06,06,22,09}, lit=1, type="throne", filled=2 })
 des.region(selection.area(27,06,43,09), "lit")
 -- Portal arrival point
 des.levregion({ region = {20,14,20,14}, type="branch" })
+-- Ceilings
+local interior = selection.floodfill(00,00):negate():filter_mapchar('.'):grow()
+des.add_ceiling(interior)
 -- Stairs
 des.stair("down", 40,7)
 -- Doors
diff --git a/dat/Mon-loca.lua b/dat/Mon-loca.lua
index 93d24ea94d..8e563d0087 100644
--- a/dat/Mon-loca.lua
+++ b/dat/Mon-loca.lua
@@ -39,6 +39,10 @@ des.region(selection.area(62,03,72,11), "unlit")
 des.teleport_region({ region={00,00,06,04}, dir="down" })
 des.teleport_region({ region={62,03,72,11}, dir="up" })
 
+-- Ceilings
+local covered = selection.floodfill(67, 4):grow() + selection.floodfill(67, 7)
+des.add_ceiling(covered)
+
 -- Stairs
 des.stair("up", 00,00)
 des.stair("down", 67,07)
diff --git a/dat/Mon-strt.lua b/dat/Mon-strt.lua
index 689539bcb5..aab6a0452b 100644
--- a/dat/Mon-strt.lua
+++ b/dat/Mon-strt.lua
@@ -41,6 +41,11 @@ des.region(selection.area(00,00,75,19), "lit")
 
 local spacelocs = selection.floodfill(05,04);
 
+-- Ceilings
+local covered = selection.area(55,14, 65,19) | selection.area(54,15, 66,18)
+                  | selection.floodfill(40,09):grow()
+des.add_ceiling(covered)
+
 -- Portal arrival point
 des.levregion({ region = {02,10,02,10}, type="branch" })
 
diff --git a/dat/Pri-loca.lua b/dat/Pri-loca.lua
index 984a04b9a0..99361d6486 100644
--- a/dat/Pri-loca.lua
+++ b/dat/Pri-loca.lua
@@ -31,6 +31,8 @@ des.region({ region={09,00, 30,01}, lit=0, type="morgue", filled=1 })
 des.region({ region={09,12, 30,13}, lit=0, type="morgue", filled=1 })
 des.region({ region={31,00, 39,13}, lit=0, type="morgue", filled=1 })
 des.region({ region={11,03, 29,10}, lit=1, type="temple", filled=1, irregular=1 })
+-- Ceilings
+des.add_ceiling(selection.area(10, 2, 30, 11))
 -- The altar inside the temple
 des.altar({ x=20,y=07, align="noalign", type="shrine" })
 des.monster({ id = "aligned cleric", x=20, y=07, align="noalign", peaceful = 0 })
diff --git a/dat/Pri-strt.lua b/dat/Pri-strt.lua
index 457949ccbb..68c25b5eec 100644
--- a/dat/Pri-strt.lua
+++ b/dat/Pri-strt.lua
@@ -47,6 +47,9 @@ local spacelocs = selection.floodfill(05,04);
 
 -- Portal arrival point
 des.levregion({ region = {05,04,05,04}, type="branch" })
+-- Ceilings
+local covered = selection.area(20,03, 55,16) | selection.area(18,08, 20,11)
+des.add_ceiling(covered)
 -- Stairs
 des.stair("down", 52,09)
 -- Doors
diff --git a/dat/Sam-loca.lua b/dat/Sam-loca.lua
index 87c08e0cf2..0e5ecc977f 100644
--- a/dat/Sam-loca.lua
+++ b/dat/Sam-loca.lua
@@ -31,6 +31,12 @@ des.map([[
 ]]);
 -- Dungeon Description
 des.region(selection.area(00,00,75,19), "lit")
+-- Ceiling
+local covered = selection.floodfill(00,00, true):negate():filter_mapchar('.')
+-- interior courtyard: roofed over out of concern players will waste scrolls of
+-- earth not realizing it's a roofless area
+-- covered = covered - selection.area(24,07,51,12)
+des.add_ceiling(covered:grow())
 -- Doors
 des.door("locked",22,04)
 des.door("locked",22,15)
diff --git a/dat/Sam-strt.lua b/dat/Sam-strt.lua
index cfc04083b7..6db56d54bb 100644
--- a/dat/Sam-strt.lua
+++ b/dat/Sam-strt.lua
@@ -38,6 +38,9 @@ des.map([[
 -- Dungeon Description
 des.region(selection.area(00,00,75,19), "lit")
 des.region({ region={18,03, 26,07}, lit=1, type="throne", filled=2 })
+-- Ceilings
+local covered = selection.area(10,02,60,11) | selection.area(42,12,60,17)
+des.add_ceiling(covered)
 -- Portal arrival zone
 des.levregion({ region = {62,12,70,17}, type="branch" })
 -- Stairs
diff --git a/dat/Tou-strt.lua b/dat/Tou-strt.lua
index bac7845f80..5aeef544ee 100644
--- a/dat/Tou-strt.lua
+++ b/dat/Tou-strt.lua
@@ -45,6 +45,10 @@ des.region(selection.area(34,02,39,04), "unlit")
 des.region(selection.area(41,02,53,04), "unlit")
 des.region(selection.area(55,02,60,04), "unlit")
 des.region(selection.area(62,02,67,04), "lit")
+-- Ceilings
+local covered = selection.area(06,09, 12,13) | selection.area(03,15, 09,19)
+                  | selection.area(16,15, 22,19) | selection.area(24,00, 72,07)
+des.add_ceiling(covered)
 -- Stairs
 des.stair("down", 66,03)
 -- Portal arrival point
diff --git a/dat/Val-strt.lua b/dat/Val-strt.lua
index 13dfccdcb5..76648fb88a 100644
--- a/dat/Val-strt.lua
+++ b/dat/Val-strt.lua
@@ -42,6 +42,8 @@ local inside = selection.floodfill(34,10) + selection.floodfill(34,06) + selecti
 local outside = (everything:filter_mapchar('.') + alltheice) - inside
 local init_monster_area = outside & selection.area(17,00,75,19):grow()
 des.region(everything, "lit")
+-- Ceilings
+des.add_ceiling(inside:clone():grow())
 -- Lava vents surrounded by water
 local pools = selection.new()
 local function growths()
diff --git a/dat/Wiz-loca.lua b/dat/Wiz-loca.lua
index 33460d92a1..acb3fd51ce 100644
--- a/dat/Wiz-loca.lua
+++ b/dat/Wiz-loca.lua
@@ -72,6 +72,8 @@ des.region({ region={48,10,54,10}, lit=0, type="ordinary", irregular=1,
              end
 })
 
+-- Ceilings
+des.add_ceiling(selection.area(36,03, 66,17))
 -- Doors
 des.door("locked",55,08)
 des.door("locked",55,12)
diff --git a/dat/Wiz-strt.lua b/dat/Wiz-strt.lua
index 285530774a..f49e3ba4ad 100644
--- a/dat/Wiz-strt.lua
+++ b/dat/Wiz-strt.lua
@@ -35,7 +35,11 @@ des.map([[
 ......................CCC.C.................................................
 ]]);
 
--- first do cloud everywhere
+-- Add ceilings before anything else, so floodfill will work
+local covered = selection.floodfill(00,00):negate():filter_mapchar('.'):grow()
+                  | selection.area(11,08, 35,12)
+des.add_ceiling(covered)
+-- do cloud everywhere
 des.replace_terrain({ region={0,0, 75,19}, fromterrain=".", toterrain="C", chance=10 })
 -- then replace clouds inside the tower back to floor
 des.replace_terrain({ region={13,5, 33,15}, fromterrain="C", toterrain=".", chance=100 })
diff --git a/include/extern.h b/include/extern.h
index ce90664bae..dc22cf76e4 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -742,6 +742,7 @@ extern boolean Is_botlevel(d_level *);
 extern boolean Can_fall_thru(d_level *);
 extern boolean Can_dig_down(d_level *);
 extern boolean Can_rise_up(coordxy, coordxy, d_level *);
+extern boolean ceiling_exists(coordxy, coordxy);
 extern boolean has_ceiling(d_level *);
 extern boolean avoid_ceiling(d_level *);
 extern const char *surface(coordxy, coordxy);
diff --git a/include/flag.h b/include/flag.h
index 63c232eb7d..fb730c9292 100644
--- a/include/flag.h
+++ b/include/flag.h
@@ -331,6 +331,7 @@ struct instance_flags {
     boolean fireassist;      /* autowield launcher when using fire-command */
     boolean time_botl;       /* context.botl for 'time' (moves) only */
     boolean wizmgender;      /* test gender info from core in window port */
+    boolean wizceiling;      /* highlight ceilngs */
     boolean invweight;       /* display weights of items in inventory */
     boolean msg_is_alert;    /* suggest windowport should grab player's attention
                               * and request <TAB> acknowlegement */
diff --git a/include/optlist.h b/include/optlist.h
index daa5fc8333..7d0726f9a3 100644
--- a/include/optlist.h
+++ b/include/optlist.h
@@ -823,6 +823,9 @@ static int optfn_##a(int, int, boolean, char *, char *);
                 No, Yes, No, No, NoAlias,
                 "the foreground/background colors of windows")
  /* NHOPTC(windowtype) -- moved to top */
+    NHOPTB(wizceiling, Advanced, 0, opt_in, set_wizonly,
+           Off, Yes, No, No, NoAlias, &iflags.wizceiling, Term_False,
+           (char *) 0)
     NHOPTB(wizmgender, Advanced, 0, opt_in, set_wizonly,
            Off, Yes, No, No, NoAlias, &iflags.wizmgender, Term_False,
            (char *)0)
diff --git a/include/rm.h b/include/rm.h
index 50a6f95914..af636a95ed 100644
--- a/include/rm.h
+++ b/include/rm.h
@@ -251,7 +251,8 @@ struct rm {
 
     Bitfield(candig, 1);     /* Exception to Can_dig_down; was a trapdoor */
     Bitfield(uvisited, 1);   /* player has visited this space */
-    Bitfield(unused, 6);     /* currently unused - take bits out of this rather
+    Bitfield(ceiling, 1);    /* special ceiling status */
+    Bitfield(unused, 5);     /* currently unused - take bits out of this rather
                                 than overloading it as if it were a second flags
                                 field! */
 };
diff --git a/include/trap.h b/include/trap.h
index 68346b8008..cca9639f85 100644
--- a/include/trap.h
+++ b/include/trap.h
@@ -121,6 +121,7 @@ enum { Trap_Effect_Finished = 0,
                                || (ttyp) == MAGIC_TRAP  \
                                || (ttyp) == ANTI_MAGIC  \
                                || (ttyp) == POLY_TRAP)
+#define is_ceiling_trap(ttyp) ((ttyp) == ROCKTRAP || (ttyp) == RUST_TRAP)
 /* "transportation" traps */
 #define is_xport(ttyp) ((ttyp) >= TELEP_TRAP && (ttyp) <= MAGIC_PORTAL)
 
diff --git a/src/dig.c b/src/dig.c
index 7cfe54ad86..ebdd3a7264 100644
--- a/src/dig.c
+++ b/src/dig.c
@@ -1497,7 +1497,7 @@ zap_dig(void)
     if (u.dz) {
         if (!Is_airlevel(&u.uz) && !Is_waterlevel(&u.uz) && !Underwater) {
             if ((u.dz < 0 || On_stairs(u.ux, u.uy))
-                && !gl.level.flags.outdoors) {
+                && ceiling_exists(u.ux, u.uy)) {
                 int dmg;
                 if (On_stairs(u.ux, u.uy)) {
                     stairway *stway = stairway_at(u.ux, u.uy);
diff --git a/src/display.c b/src/display.c
index 12551469bf..2dc1a1c39f 100644
--- a/src/display.c
+++ b/src/display.c
@@ -2613,6 +2613,11 @@ map_glyphinfo(
                                        ? CLR_GRAY : CLR_WHITE;
         }
     }
+    if (iflags.wizceiling && wizard && isok(x, y) && levl[x][y].ceiling) {
+        glyphinfo->gm.sym.color = CLR_RED;
+        /* glyphinfo->gm.sym.symidx */ 
+        glyphinfo->gm.glyphflags |= MG_OBJPILE;
+    }
 #endif /* TEXTCOLOR */
     glyphinfo->ttychar = gs.showsyms[glyphinfo->gm.sym.symidx];
     glyphinfo->glyph = glyph;
diff --git a/src/dothrow.c b/src/dothrow.c
index ce9734e0de..ec372beee6 100644
--- a/src/dothrow.c
+++ b/src/dothrow.c
@@ -1309,7 +1309,7 @@ toss_up(struct obj *obj, boolean hitsroof)
                          && touch_petrifies(&mons[obj->corpsenm]));
     /* note: obj->quan == 1 */
 
-    if (!has_ceiling(&u.uz)) {
+    if (!ceiling_exists(u.ux, u.uy)) {
         action = "flies up into"; /* into "the sky" or "the water above" */
     } else if (hitsroof) {
         if (breaktest(obj)) {
diff --git a/src/dungeon.c b/src/dungeon.c
index 22ca20ee84..79f9a79ce0 100644
--- a/src/dungeon.c
+++ b/src/dungeon.c
@@ -1803,7 +1803,7 @@ ceiling(coordxy x, coordxy y)
     else if (Is_waterlevel(&u.uz))
         /* water plane has no surface; its air bubbles aren't below sky */
         what = "water above";
-    else if (!has_ceiling(&u.uz))
+    else if (!ceiling_exists(x, y))
         what = "sky";
     else if (Is_firelevel(&u.uz))
         what = "flames above";
@@ -1864,6 +1864,26 @@ surface(coordxy x, coordxy y)
         return "ground";
 }
 
+boolean
+ceiling_exists(coordxy x, coordxy y)
+{
+    /* no exceptions on certain levels */
+    if (Is_airlevel(&u.uz) || Is_waterlevel(&u.uz))
+        return FALSE;
+    if (!gl.level.flags.outdoors)
+        return TRUE;
+    /* if we're given 0,0 or similar out-of-bounds candidate, just return
+       the default ceiling state for the level -- after previous checks it
+       must be no-ceiling */
+    if (!isok(x, y))
+        return FALSE;
+    /* now check for exceptions */
+    if (levl[x][y].ceiling)
+        return TRUE;
+
+    return FALSE;
+}
+
 /*
  * It is expected that the second argument of get_level is a depth value,
  * either supplied by the user (teleport control) or randomly generated.
diff --git a/src/mklev.c b/src/mklev.c
index d80263b6fc..3cf71e17ed 100644
--- a/src/mklev.c
+++ b/src/mklev.c
@@ -1965,7 +1965,7 @@ mktrap(
             case RUST_TRAP:
             case ROCKTRAP:
                 /* certain traps that rely on a ceiling to make sense */
-                if (!has_ceiling(&u.uz))
+                if (tm && !ceiling_exists(tm->x, tm->y))
                     kind = NO_TRAP;
             }
         } while (kind == NO_TRAP);
@@ -1978,7 +1978,8 @@ mktrap(
         m = *tm;
     } else {
         register int tryct = 0;
-        boolean avoid_boulder = (is_pit(kind) || is_hole(kind));
+        boolean avoid_boulder = (is_pit(kind) || is_hole(kind)),
+                need_ceiling = is_ceiling_trap(kind);
 
         /* Try up to 200 times to find a random coordinate for the trap. */
         do {
@@ -1989,7 +1990,8 @@ mktrap(
             else if (!somexyspace(croom, &m))
                 return;
         } while (occupied(m.x, m.y)
-                 || (avoid_boulder && sobj_at(BOULDER, m.x, m.y)));
+                 || (avoid_boulder && sobj_at(BOULDER, m.x, m.y))
+                 || (need_ceiling && !ceiling_exists(m.x, m.y)));
     }
 
     t = maketrap(m.x, m.y, kind);
diff --git a/src/mon.c b/src/mon.c
index a1f4c73e21..39e22b9835 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -159,14 +159,14 @@ sanity_check_single_mon(
         if (ceiling_hider(mptr)
             /* normally !accessible would be overridable with passes_walls,
                but not for hiding on the ceiling */
-            && (!has_ceiling(&u.uz) ||
-                !(levl[mx][my].typ == POOL
-                  || levl[mx][my].typ == MOAT
-                  || levl[mx][my].typ == LAVAPOOL
-                  || accessible(mx, my))))
+            && (!ceiling_exists(mx, my)
+                || !(levl[mx][my].typ == POOL
+                    || levl[mx][my].typ == MOAT
+                    || levl[mx][my].typ == LAVAPOOL
+                    || accessible(mx, my))))
             impossible("ceiling hider hiding %s (%s)",
-                       !has_ceiling(&u.uz) ? "without ceiling"
-                                           : "in solid stone",
+                       !ceiling_exists(mx, my) ? "without ceiling"
+                                               : "in solid stone",
                        msg);
         if (mtmp->mtrapped && (t = t_at(mx, my)) != 0 && !is_pit(t->ttyp))
             impossible("hiding while trapped in a non-pit (%s)", msg);
@@ -4634,7 +4634,7 @@ restrap(struct monst *mtmp)
         set_mimic_sym(mtmp);
         return TRUE;
     } else if (levl[mtmp->mx][mtmp->my].typ == ROOM
-               && has_ceiling(&u.uz)) {
+               && ceiling_exists(mtmp->mx, mtmp->my)) {
         mtmp->mundetected = 1;
         return TRUE;
     }
diff --git a/src/muse.c b/src/muse.c
index 2fdb3bb4b2..e687885f2b 100644
--- a/src/muse.c
+++ b/src/muse.c
@@ -1443,6 +1443,7 @@ find_offensive(struct monst *mtmp)
                 || !rn2(10))
             && dist2(mtmp->mx, mtmp->my, mtmp->mux, mtmp->muy) <= 2
             && mtmp->mcansee && haseyes(mtmp->data)
+            && ceiling_exists(mtmp->mx, mtmp->my)
             && (!In_endgame(&u.uz) || Is_earthlevel(&u.uz))) {
             gm.m.offensive = obj;
             gm.m.has_offense = MUSE_SCR_EARTH;
@@ -1783,6 +1784,7 @@ use_offensive(struct monst *mtmp)
             for (y = mmy - 1; y <= mmy + 1; y++) {
                 /* Is this a suitable spot? */
                 if (isok(x, y) && !closed_door(x, y)
+                    && ceiling_exists(x, y)
                     && !IS_ROCK(levl[x][y].typ) && !IS_AIR(levl[x][y].typ)
                     && (((x == mmx) && (y == mmy)) ? !is_blessed : !is_cursed)
                     && (x != u.ux || y != u.uy)) {
@@ -1791,7 +1793,8 @@ use_offensive(struct monst *mtmp)
             }
         }
         /* Attack the player */
-        if (distmin(mmx, mmy, u.ux, u.uy) == 1 && !is_cursed) {
+        if (distmin(mmx, mmy, u.ux, u.uy) == 1 && !is_cursed
+            && ceiling_exists(u.ux, u.uy)) {
             drop_boulder_on_player(confused, !is_cursed, FALSE, TRUE);
         }
 
diff --git a/src/options.c b/src/options.c
index 2b66e325b4..fa562bb8f9 100644
--- a/src/options.c
+++ b/src/options.c
@@ -5004,6 +5004,7 @@ optfn_boolean(int optidx, int req, boolean negated, char *opts, char *op)
             if (iflags.use_color)
                 go.opt_need_redraw = TRUE; /* darkroom refresh */
             break;
+        case opt_wizceiling:
         case opt_wizmgender:
         case opt_showrace:
         case opt_use_inverse:
diff --git a/src/polyself.c b/src/polyself.c
index d232b2bd57..1cfdd57e91 100644
--- a/src/polyself.c
+++ b/src/polyself.c
@@ -1851,7 +1851,7 @@ dohide(void)
         }
     }
     /* Planes of Air and Water */
-    if (on_ceiling && !has_ceiling(&u.uz)) {
+    if (on_ceiling && !ceiling_exists(u.ux, u.uy)) {
         There("is nowhere to hide above you.");
         u.uundetected = 0;
         return ECMD_OK;
diff --git a/src/potion.c b/src/potion.c
index bd0697188e..a0ad52335a 100644
--- a/src/potion.c
+++ b/src/potion.c
@@ -1400,7 +1400,7 @@ peffect_levitation(struct obj *otmp)
             /* in case we're already Levitating, which would have
                resulted in incrementing 'nothing' */
             gp.potion_nothing = 0; /* not nothing after all */
-        } else if (has_ceiling(&u.uz)) {
+        } else if (ceiling_exists(u.ux, u.uy)) {
             int dmg = rnd(!uarmh ? 10 : !is_hard(uarmh) ? 6 : 3);
 
             You("hit your %s on the %s.", body_part(HEAD),
diff --git a/src/read.c b/src/read.c
index b722c90e69..e7a4ca2224 100644
--- a/src/read.c
+++ b/src/read.c
@@ -1984,7 +1984,7 @@ seffect_earth(struct obj **sobjp)
         }
         pline("The earth moves around you!");
     }
-    else if (has_ceiling(&u.uz)
+    else if (ceiling_exists(u.ux, u.uy)
              && (!In_endgame(&u.uz) || Is_earthlevel(&u.uz))) {
         coordxy x, y;
         int nboulders = 0;
@@ -2016,6 +2016,7 @@ seffect_earth(struct obj **sobjp)
                 for (y = u.uy - 1; y <= u.uy + 1; y++) {
                     /* Is this a suitable spot? */
                     if (isok(x, y) && !closed_door(x, y)
+                        && ceiling_exists(x, y)
                         && !IS_ROCK(levl[x][y].typ)
                         && !IS_AIR(levl[x][y].typ)
                         && (x != u.ux || y != u.uy)) {
@@ -2025,7 +2026,7 @@ seffect_earth(struct obj **sobjp)
                 }
             }
         /* Attack the player */
-        if (!sblessed) {
+        if (!sblessed && ceiling_exists(u.ux, u.uy)) {
             drop_boulder_on_player(FALSE, !scursed, TRUE, FALSE);
         } else if (!nboulders)
             pline("But nothing else happens.");
diff --git a/src/sp_lev.c b/src/sp_lev.c
index 9a15c99c47..af2bdb4b02 100644
--- a/src/sp_lev.c
+++ b/src/sp_lev.c
@@ -102,6 +102,8 @@ static void get_table_xy_or_coord(lua_State *, lua_Integer *, lua_Integer *);
 static int get_table_region(lua_State *, const char *, lua_Integer *,
                         lua_Integer *, lua_Integer *, lua_Integer *, boolean);
 static void set_wallprop_in_selection(lua_State *, int);
+static void set_prop_in_selection(lua_State *, select_iter_func, int);
+static void sel_set_ceiling(coordxy, coordxy, genericptr_t);
 static coordxy random_wdir(void);
 static int floodfillchk_match_under(coordxy, coordxy);
 static int floodfillchk_match_accessible(coordxy, coordxy);
@@ -144,6 +146,7 @@ int lspo_mineralize(lua_State *);
 int lspo_monster(lua_State *);
 int lspo_non_diggable(lua_State *);
 int lspo_non_passwall(lua_State *);
+int lspo_add_ceiling(lua_State *);
 int lspo_object(lua_State *);
 int lspo_portal(lua_State *);
 int lspo_random_corridors(lua_State *);
@@ -6668,6 +6671,12 @@ lspo_wall_property(lua_State *L)
 
 static void
 set_wallprop_in_selection(lua_State *L, int prop)
+{
+    set_prop_in_selection(L, sel_set_wall_property, prop);
+}
+
+static void
+set_prop_in_selection(lua_State *L, select_iter_func set, int prop)
 {
     int argc = lua_gettop(L);
     boolean freesel = FALSE;
@@ -6684,7 +6693,7 @@ set_wallprop_in_selection(lua_State *L, int prop)
     }
 
     if (sel) {
-        selection_iterate(sel, sel_set_wall_property, (genericptr_t) &prop);
+        selection_iterate(sel, set, (genericptr_t) &prop);
         if (freesel)
             selection_free(sel, TRUE);
     }
@@ -6708,6 +6717,25 @@ lspo_non_passwall(lua_State *L)
     return 0;
 }
 
+static void
+sel_set_ceiling(coordxy x, coordxy y, genericptr_t arg)
+{
+    int val = *(int *)arg;
+
+    levl[x][y].ceiling = val;
+}
+
+/* should be used for 'outdoors' flagged levels, to specify areas which have
+ * ceilings */
+/* add_ceiling(selection); */
+/* add_ceiling(); */
+int
+lspo_add_ceiling(lua_State *L)
+{
+    set_prop_in_selection(L, sel_set_ceiling, 1);
+    return 0;
+}
+
 #if 0
 /*ARGSUSED*/
 static void
@@ -7173,6 +7201,7 @@ static const struct luaL_Reg nhl_functions[] = {
     { "wall_property", lspo_wall_property },
     { "non_diggable", lspo_non_diggable },
     { "non_passwall", lspo_non_passwall },
+    { "add_ceiling", lspo_add_ceiling },
     { "teleport_region", lspo_teleport_region },
     { "reset_level", lspo_reset_level },
     { "finalize_level", lspo_finalize_level },
diff --git a/src/zap.c b/src/zap.c
index 881a7c15e1..b0303ab53b 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -3225,9 +3225,8 @@ zap_updown(struct obj *obj) /* wand or spell */
             else
                 destroy_drawbridge(xx, yy);
             disclose = TRUE;
-        } else if (striking && u.dz < 0 && rn2(3) && !Is_airlevel(&u.uz)
-                   && !Is_waterlevel(&u.uz) && !Underwater
-                   && !Is_qstart(&u.uz)) {
+        } else if (striking && u.dz < 0 && rn2(3)
+                   && ceiling_exists(x, y) && !Underwater) {
             int dmg;
             /* similar to zap_dig() */
             pline("A rock is dislodged from the %s and falls on your %s.",