diff -Npbaur -x '*~' -x '#*#' nethack-3.4.3/include/extern.h nethack-rust/include/extern.h
--- nethack-3.4.3/include/extern.h	2003-12-08 10:39:13.000000000 +1100
+++ nethack-rust/include/extern.h	2006-06-08 19:06:06.000000000 +1000
@@ -1196,6 +1196,7 @@ E boolean FDECL(onscary, (int,int,struct
 E void FDECL(monflee, (struct monst *, int, BOOLEAN_P, BOOLEAN_P));
 E int FDECL(dochug, (struct monst *));
 E int FDECL(m_move, (struct monst *,int));
+E void FDECL(dissolve_bars, (int,int));
 E boolean FDECL(closed_door, (int,int));
 E boolean FDECL(accessible, (int,int));
 E void FDECL(set_apparxy, (struct monst *));
diff -Npbaur -x '*~' -x '#*#' nethack-3.4.3/src/hack.c nethack-rust/src/hack.c
--- nethack-3.4.3/src/hack.c	2003-12-08 10:39:13.000000000 +1100
+++ nethack-rust/src/hack.c	2006-06-08 19:06:49.000000000 +1000
@@ -561,6 +561,11 @@ int mode;
 	if (Passes_walls && may_passwall(x,y)) {
 	    ;	/* do nothing */
 	} else if (tmpr->typ == IRONBARS) {
+	    if ((dmgtype(youmonst.data, AD_RUST) ||
+		 dmgtype(youmonst.data, AD_CORR))) {
+		You("eat through the bars.");
+		dissolve_bars(x,y);
+	    }
 	    if (!(Passes_walls || passes_bars(youmonst.data)))
 		return FALSE;
 	} else if (tunnels(youmonst.data) && !needspick(youmonst.data)) {
diff -Npbaur -x '*~' -x '#*#' nethack-3.4.3/src/mondata.c nethack-rust/src/mondata.c
--- nethack-3.4.3/src/mondata.c	2003-12-08 10:39:13.000000000 +1100
+++ nethack-rust/src/mondata.c	2006-06-08 18:32:06.000000000 +1000
@@ -252,8 +252,9 @@ boolean
 passes_bars(mptr)
 struct permonst *mptr;
 {
-    return (boolean) (passes_walls(mptr) || amorphous(mptr) ||
+    return (boolean)(passes_walls(mptr) || amorphous(mptr) ||
 		      is_whirly(mptr) || verysmall(mptr) ||
+		     dmgtype(mptr, AD_CORR) || dmgtype(mptr, AD_RUST) ||
 		      (slithy(mptr) && !bigmonst(mptr)));
 }
 
diff -Npbaur -x '*~' -x '#*#' nethack-3.4.3/src/monmove.c nethack-rust/src/monmove.c
--- nethack-3.4.3/src/monmove.c	2003-12-08 10:39:13.000000000 +1100
+++ nethack-rust/src/monmove.c	2006-06-14 10:14:18.000000000 +1000
@@ -1125,7 +1125,14 @@ postmov:
 			    add_damage(mtmp->mx, mtmp->my, 0L);
 		    }
 		} else if (levl[mtmp->mx][mtmp->my].typ == IRONBARS) {
-			if (flags.verbose && canseemon(mtmp))
+		    if (dmgtype(ptr,AD_RUST) || dmgtype(ptr,AD_CORR)) {
+			if (canseemon(mtmp)) {
+			    pline("%s eats through the iron bars.", 
+				  Monnam(mtmp)); 
+			}
+			dissolve_bars(mtmp->mx, mtmp->my);
+		    }
+		    else if (flags.verbose && canseemon(mtmp))
 			    Norep("%s %s %s the iron bars.", Monnam(mtmp),
 				  /* pluralization fakes verb conjugation */
 				  makeplural(locomotion(ptr, "pass")),
@@ -1217,6 +1224,14 @@ postmov:
 #endif /* OVL0 */
 #ifdef OVL2
 
+void
+dissolve_bars(x, y)
+register int x, y;
+{
+    levl[x][y].typ = (Is_special(&u.uz) || *in_rooms(x,y,0)) ? ROOM : CORR; 
+    newsym(x, y);    
+}
+
 boolean
 closed_door(x, y)
 register int x, y;