diff --git a/doc/fixes34.4 b/doc/fixes34.4
index 26d7a7237..df1414a9c 100644
--- a/doc/fixes34.4
+++ b/doc/fixes34.4
@@ -188,6 +188,8 @@ make gender of quest leaders and nemeses consistent with data.base and
 Orion and Norn should be giant sized
 Orion, Norn, Cyclops and Lord Surtur should be able to tear webs
 typo in Gnome King cellar message
+ensure monsters cannot teleport to or be created outside nonpassable bounds
+	of special levels
 
 
 Platform- and/or Interface-Specific Fixes
diff --git a/src/sp_lev.c b/src/sp_lev.c
index 34194b80e..6b5898f96 100644
--- a/src/sp_lev.c
+++ b/src/sp_lev.c
@@ -2114,6 +2114,7 @@ dlb *fd;
     xchar   mustfill[(MAXNROFROOMS+1)*2];
     struct trap *badtrap;
     boolean has_bounds;
+    boolean bounds_nodigpass;
 
     (void) memset((genericptr_t)&Map[0][0], 0, sizeof Map);
     load_common_data(fd, SP_LEV_MAZE);
@@ -2135,6 +2136,9 @@ dlb *fd;
 	    }
     }
 
+    /* if filling with stone, surrounding stone may all be nondig, nonpass */
+    bounds_nodigpass = (filling == STONE);
+
     /* Start reading the file */
     Fread((genericptr_t) &numpart, 1, sizeof(numpart), fd);
 						/* Number of parts */
@@ -2184,6 +2188,7 @@ dlb *fd;
 	    ystart = 0;
 	    xsize = COLNO-1;
 	    ysize = ROWNO;
+	    bounds_nodigpass = FALSE;
 	} else {
 	    /* Load the map */
 	    for(y = ystart; y < ystart+ysize; y++)
@@ -2445,6 +2450,38 @@ dlb *fd;
 				  tmpdig.x2, tmpdig.y2, W_NONPASSWALL);
 	}
 
+	/* walk bounds, reset bounds_nodigpass diggable or passable */
+	if (bounds_nodigpass) {
+	    for (x = xstart; x < xstart+xsize; x++) {
+		if (!IS_STWALL(levl[x][ystart].typ) ||
+		    (levl[x][ystart].wall_info &
+		     (W_NONDIGGABLE|W_NONPASSWALL)) !=
+		    (W_NONDIGGABLE|W_NONPASSWALL) ||
+		    !IS_STWALL(levl[x][ystart+ysize-1].typ) ||
+		    (levl[x][ystart+ysize-1].wall_info &
+		     (W_NONDIGGABLE|W_NONPASSWALL)) !=
+		    (W_NONDIGGABLE|W_NONPASSWALL)) {
+		    bounds_nodigpass = FALSE;
+		    break;
+		}
+	    }
+	}
+	if (bounds_nodigpass) {
+	    for(y = ystart; y < ystart+ysize; y++) {
+		if (!IS_STWALL(levl[xstart][y].typ) ||
+		    (levl[xstart][y].wall_info &
+		     (W_NONDIGGABLE|W_NONPASSWALL)) !=
+		    (W_NONDIGGABLE|W_NONPASSWALL) ||
+		    !IS_STWALL(levl[xstart+xsize-1][y].typ) ||
+		    (levl[xstart+xsize-1][y].wall_info &
+		     (W_NONDIGGABLE|W_NONPASSWALL)) !=
+		    (W_NONDIGGABLE|W_NONPASSWALL)) {
+		    bounds_nodigpass = FALSE;
+		    break;
+		}
+	    }
+	}
+
 	Fread((genericptr_t) &n, 1, sizeof(n), fd);
 						/* Number of ladders */
 	while(n--) {
@@ -2643,6 +2680,19 @@ dlb *fd;
 		    (void) maketrap(mm.x, mm.y, trytrap);
 	    }
     }
+
+    /*
+     * If bounds_nodigpass, and no mazewalks, mark all locations outside
+     * the map are mapped as nodig and nopass as well.  This avoids passwall
+     * monsters like Xorns from appearing outside the accessible area.
+     */
+    if (bounds_nodigpass && !nwalk_sav) {
+	for(x = 1; x < COLNO; x++)
+	    for(y = 0; y < ROWNO; y++)
+	    if(!Map[x][y])
+		levl[x][y].wall_info |= W_NONDIGGABLE|W_NONPASSWALL;
+    }
+
     return TRUE;
 }