diff --git a/hawk/lib/Hawk.hpp b/hawk/lib/Hawk.hpp
index 187c75c7..fa790b19 100644
--- a/hawk/lib/Hawk.hpp
+++ b/hawk/lib/Hawk.hpp
@@ -45,7 +45,7 @@
 #endif
 
 /// \file
-/// AWK Interpreter
+/// Hawk Interpreter
 
 /////////////////////////////////
 HAWK_BEGIN_NAMESPACE(HAWK)
diff --git a/hawk/lib/HawkStd.hpp b/hawk/lib/HawkStd.hpp
index 06d74a3a..c2553301 100644
--- a/hawk/lib/HawkStd.hpp
+++ b/hawk/lib/HawkStd.hpp
@@ -30,7 +30,7 @@
 #include <Hawk.hpp>
 
 /// \file
-/// Standard AWK Interpreter
+/// Standard Hawk Interpreter
 
 /////////////////////////////////
 HAWK_BEGIN_NAMESPACE(HAWK)
diff --git a/hawk/lib/hawk-prv.h b/hawk/lib/hawk-prv.h
index 0384985a..db44d68c 100644
--- a/hawk/lib/hawk-prv.h
+++ b/hawk/lib/hawk-prv.h
@@ -491,6 +491,13 @@ struct hawk_rtx_t
 		hawk_oow_t expr; /* expression */
 	} depth;
 
+	struct
+	{
+		hawk_val_t** ptr;
+		hawk_oow_t size;
+		hawk_oow_t capa;
+	} forin; /* keys for for (x in y) ... */
+
 	hawk_oow_t  errmsg_len; /* used by errbfmt() and errufmt(). don't rely on this. some other funtions don't set this properly */
 	hawk_ooch_t errmsg_backup[HAWK_ERRMSG_CAPA];
 #if defined(HAWK_OOCH_IS_BCH)
diff --git a/hawk/lib/hawk-rbt.h b/hawk/lib/hawk-rbt.h
index 33384741..f73d03eb 100644
--- a/hawk/lib/hawk-rbt.h
+++ b/hawk/lib/hawk-rbt.h
@@ -230,6 +230,21 @@ enum hawk_rbt_style_kind_t
 
 typedef enum hawk_rbt_style_kind_t  hawk_rbt_style_kind_t;
 
+typedef struct hawk_rbt_itr_t hawk_rbt_itr_t;
+struct hawk_rbt_itr_t
+{
+	hawk_rbt_pair_t* pair;
+	hawk_rbt_pair_t* _prev;
+	unsigned int _dir: 1; /* 0 or 1 */
+	unsigned int _state: 8;
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+	unsigned int _prot_updated: 1;
+	hawk_oow_t _prot_seqno;
+	hawk_rbt_itr_t* _prot_prev;
+	hawk_rbt_itr_t* _prot_next;
+#endif
+};
+
 /**
  * The hawk_rbt_t type defines a red-black tree.
  */
@@ -241,19 +256,11 @@ struct hawk_rbt_t
 	hawk_rbt_pair_t         xnil;      /**< internal nil node */
 	hawk_oow_t              size;      /**< number of pairs */
 	hawk_rbt_pair_t*        root;      /**< root pair */
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+	hawk_rbt_itr_t          _prot_itr; /**< protected iterators */
+#endif
 };
 
-
-struct hawk_rbt_itr_t
-{
-	hawk_rbt_pair_t* pair;
-	hawk_rbt_pair_t* _prev;
-	int _dir; /* 0 or 1 */
-	int _state;
-};
-
-typedef struct hawk_rbt_itr_t hawk_rbt_itr_t;
-
 /**
  * The HAWK_RBT_COPIER_SIMPLE macros defines a copier that remembers the
  * pointer and length of data in a pair.
@@ -564,6 +571,18 @@ HAWK_EXPORT hawk_rbt_pair_t* hawk_rbt_getnextpair (
 	hawk_rbt_itr_t*  itr
 );
 
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+HAWK_EXPORT void hawk_rbt_protectitr (
+	hawk_rbt_t*      rbt,
+	hawk_rbt_itr_t*  itr
+);
+
+HAWK_EXPORT void hawk_rbt_unprotectitr (
+	hawk_rbt_t*      rbt,
+	hawk_rbt_itr_t*  itr
+);
+#endif
+
 /**
  * The hawk_rbt_walk() function traverses a red-black tree in preorder 
  * from the leftmost child.
diff --git a/hawk/lib/hawk.h b/hawk/lib/hawk.h
index 952a7512..f26016cb 100644
--- a/hawk/lib/hawk.h
+++ b/hawk/lib/hawk.h
@@ -373,7 +373,7 @@ enum hawk_nde_type_t
 	HAWK_NDE_WHILE,
 	HAWK_NDE_DOWHILE,
 	HAWK_NDE_FOR,
-	HAWK_NDE_FOREACH,
+	HAWK_NDE_FORIN,
 	HAWK_NDE_BREAK,
 	HAWK_NDE_CONTINUE,
 	HAWK_NDE_RETURN,
diff --git a/hawk/lib/parse.c b/hawk/lib/parse.c
index efb52059..83827357 100644
--- a/hawk/lib/parse.c
+++ b/hawk/lib/parse.c
@@ -2613,7 +2613,7 @@ static hawk_nde_t* parse_for (hawk_t* awk, const hawk_loc_t* xloc)
 	hawk_nde_t* init = HAWK_NULL, * test = HAWK_NULL;
 	hawk_nde_t* incr = HAWK_NULL, * body = HAWK_NULL;
 	hawk_nde_for_t* nde_for; 
-	hawk_nde_foreach_t* nde_foreach;
+	hawk_nde_forin_t* nde_forin;
 	hawk_loc_t ploc;
 
 	if (!MATCH(awk,TOK_LPAREN))
@@ -2628,17 +2628,17 @@ static hawk_nde_t* parse_for (hawk_t* awk, const hawk_loc_t* xloc)
 		/* this line is very ugly. it checks the entire next 
 		 * expression or the first element in the expression
 		 * is wrapped by a parenthesis */
-		int no_foreach = MATCH(awk,TOK_LPAREN);
+		int no_forin = MATCH(awk,TOK_LPAREN);
 
 		ploc = awk->tok.loc;
 		init = parse_expr_withdc (awk, &ploc);
 		if (init == HAWK_NULL) goto oops;
 
-		if (!no_foreach && init->type == HAWK_NDE_EXP_BIN &&
+		if (!no_forin && init->type == HAWK_NDE_EXP_BIN &&
 		    ((hawk_nde_exp_t*)init)->opcode == HAWK_BINOP_IN &&
 		    is_plain_var(((hawk_nde_exp_t*)init)->left))
 		{	
-			/* switch to foreach - for (x in y) */
+			/* switch to forin - for (x in y) */
 			
 			if (!MATCH(awk,TOK_RPAREN))
 			{
@@ -2652,20 +2652,20 @@ static hawk_nde_t* parse_for (hawk_t* awk, const hawk_loc_t* xloc)
 			body = parse_statement (awk, &ploc);
 			if (body == HAWK_NULL) goto oops;
 
-			nde_foreach = (hawk_nde_foreach_t*) hawk_callocmem (
-				awk, HAWK_SIZEOF(*nde_foreach));
-			if (nde_foreach == HAWK_NULL)
+			nde_forin = (hawk_nde_forin_t*) hawk_callocmem (
+				awk, HAWK_SIZEOF(*nde_forin));
+			if (nde_forin == HAWK_NULL)
 			{
 				ADJERR_LOC (awk, xloc);
 				goto oops;
 			}
 
-			nde_foreach->type = HAWK_NDE_FOREACH;
-			nde_foreach->loc = *xloc;
-			nde_foreach->test = init;
-			nde_foreach->body = body;
+			nde_forin->type = HAWK_NDE_FORIN;
+			nde_forin->loc = *xloc;
+			nde_forin->test = init;
+			nde_forin->body = body;
 
-			return (hawk_nde_t*)nde_foreach;
+			return (hawk_nde_t*)nde_forin;
 		}
 
 		if (!MATCH(awk,TOK_SEMICOLON)) 
diff --git a/hawk/lib/rbt.c b/hawk/lib/rbt.c
index 639073d1..9eacbc0e 100644
--- a/hawk/lib/rbt.c
+++ b/hawk/lib/rbt.c
@@ -235,6 +235,11 @@ int hawk_rbt_init (hawk_rbt_t* rbt, hawk_gem_t* gem, int kscale, int vscale)
 	/* root is set to nil initially */
 	rbt->root = &rbt->xnil;
 
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+	rbt->_prot_itr._prot_next = &rbt->_prot_itr;
+	rbt->_prot_itr._prot_prev = &rbt->_prot_itr;
+#endif
+
 	return 0;
 }
 
@@ -408,8 +413,7 @@ static void adjust (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair)
 	}
 }
 
-static hawk_rbt_pair_t* change_pair_val (
-	hawk_rbt_t* rbt, hawk_rbt_pair_t* pair, void* vptr, hawk_oow_t vlen)
+static hawk_rbt_pair_t* change_pair_val (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair, void* vptr, hawk_oow_t vlen)
 {
 	if (VPTR(pair) == vptr && VLEN(pair) == vlen)
 	{
@@ -769,7 +773,7 @@ static void adjust_for_delete (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair, hawk_rbt_
 
 static void delete_pair (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair)
 {
-	hawk_rbt_pair_t* x, * y, * par;
+	hawk_rbt_pair_t* x, * y, * parent;
 
 	HAWK_ASSERT (pair && !IS_NIL(rbt,pair));
 
@@ -786,15 +790,15 @@ static void delete_pair (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair)
 
 	x = IS_NIL(rbt,y->left)? y->right: y->left;
 
-	par = y->parent;
-	if (!IS_NIL(rbt,x)) x->parent = par;
+	parent = y->parent;
+	if (!IS_NIL(rbt,x)) x->parent = parent;
 
-	if (par)
+	if (parent)
 	{
-		if (y == par->left)
-			par->left = x;
+		if (y == parent->left)
+			parent->left = x;
 		else
-			par->right = x;
+			parent->right = x;
 	}
 	else
 	{
@@ -804,16 +808,15 @@ static void delete_pair (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair)
 	if (y == pair)
 	{
 		if (y->color == HAWK_RBT_BLACK && !IS_NIL(rbt,x))
-			adjust_for_delete (rbt, x, par);
+			adjust_for_delete (rbt, x, parent);
 
 		hawk_rbt_freepair (rbt, y);
 	}
 	else
 	{
 		if (y->color == HAWK_RBT_BLACK && !IS_NIL(rbt,x))
-			adjust_for_delete (rbt, x, par);
+			adjust_for_delete (rbt, x, parent);
 
-#if 1
 		if (pair->parent)
 		{
 			if (pair->parent->left == pair) pair->parent->left = y;
@@ -831,34 +834,48 @@ static void delete_pair (hawk_rbt_t* rbt, hawk_rbt_pair_t* pair)
 
 		if (pair->left->parent == pair) pair->left->parent = y;
 		if (pair->right->parent == pair) pair->right->parent = y;
-#else
-		*y = *pair;
-		if (y->parent)
-		{
-			if (y->parent->left == pair) y->parent->left = y;
-			if (y->parent->right == pair) y->parent->right = y;
-		}
-		else
-		{
-			rbt->root = y;
-		}
-
-		if (y->left->parent == pair) y->left->parent = y;
-		if (y->right->parent == pair) y->right->parent = y;
-#endif
 
 		hawk_rbt_freepair (rbt, pair);
 	}
 
 	rbt->size--;
+
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+	/* an iterator set by hawk_rbt_getfirstpair() or hawk_rbt_getnextpair(), if deleted, gets invalidated.
+	 * this protection updates registered iterators to the next valid pair if they gets deleted.
+	 * the caller may reuse the iterator if _prot_updated is set to a non-zero value */
+	if (rbt->_prot_itr._prot_next != &rbt->_prot_itr)
+	{
+		/* there are protected iterators */
+		hawk_rbt_itr_t* itr = rbt->_prot_itr._prot_next;
+		do
+		{
+			if (itr->pair == pair) 
+			{
+				hawk_oow_t seqno = itr->_prot_seqno;
+
+				/* TODO: this is slow. devise a way to get the next pair safely without traversal */
+				hawk_rbt_getfirstpair (rbt, itr);
+				while (itr->pair && itr->_prot_seqno < seqno)
+				{
+					hawk_rbt_getnextpair (rbt, itr);
+				}
+
+				itr->_prot_updated = 1;
+			}
+			itr = itr->_prot_next;
+		}
+		while (itr != &rbt->_prot_itr);
+	}
+#endif
 }
 
 int hawk_rbt_delete (hawk_rbt_t* rbt, const void* kptr, hawk_oow_t klen)
 {
 	hawk_rbt_pair_t* pair;
 
-	pair = hawk_rbt_search (rbt, kptr, klen);
-	if (pair == HAWK_NULL) return -1;
+	pair = hawk_rbt_search(rbt, kptr, klen);
+	if (!pair) return -1;
 
 	delete_pair (rbt, pair);
 	return 0;
@@ -900,7 +917,6 @@ void hawk_init_rbt_itr (hawk_rbt_itr_t* itr, int dir)
 	itr->_state = 0;
 }
 
-
 static hawk_rbt_pair_t* get_next_pair (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
 {
 	hawk_rbt_pair_t* x_cur = itr->pair;
@@ -929,7 +945,10 @@ static hawk_rbt_pair_t* get_next_pair (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
 				itr->pair = x_cur;
 				itr->_prev = prev;
 				itr->_state = 1;
-				return x_cur;	
+			#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+				itr->_prot_seqno++;
+			#endif
+				return x_cur;
 
 			resume_1:
 				if (!IS_NIL(rbt,x_cur->child[r]))
@@ -954,6 +973,9 @@ static hawk_rbt_pair_t* get_next_pair (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
 			itr->pair = x_cur;
 			itr->_prev = prev;
 			itr->_state = 2;
+		#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+			itr->_prot_seqno++;
+		#endif
 			return x_cur;
 
 		resume_2:
@@ -980,6 +1002,9 @@ static hawk_rbt_pair_t* get_next_pair (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
 		}
 	}
 
+	itr->pair = HAWK_NULL;
+	itr->_prev = HAWK_NULL;
+	itr->_state = 0;
 	return HAWK_NULL;
 }
 
@@ -988,6 +1013,12 @@ hawk_rbt_pair_t* hawk_rbt_getfirstpair (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
 	itr->pair = rbt->root;
 	itr->_prev = rbt->root->parent;
 	itr->_state = 0;
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+	itr->_prot_seqno = 0;
+	/* _prot_prev and _prot_next must be left uninitialized because of the way 
+	 * this function is called in delete_pair() for protection handling
+	 */
+#endif
 	return get_next_pair(rbt, itr);
 }
 
@@ -996,12 +1027,28 @@ hawk_rbt_pair_t* hawk_rbt_getnextpair (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
 	return get_next_pair(rbt, itr);
 }
 
+#if defined(HAWK_ENABLE_RBT_ITR_PROTECTION)
+void hawk_rbt_protectitr (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
+{
+	itr->_prot_next = &rbt->_prot_itr;
+	itr->_prot_prev = rbt->_prot_itr._prot_prev;
+	itr->_prot_prev->_prot_next = itr;
+	rbt->_prot_itr._prot_prev = itr;
+}
+
+void hawk_rbt_unprotectitr (hawk_rbt_t* rbt, hawk_rbt_itr_t* itr)
+{
+	itr->_prot_prev->_prot_next = itr->_prot_next;
+	itr->_prot_next->_prot_prev = itr->_prot_prev;
+}
+#endif
+
 void hawk_rbt_walk (hawk_rbt_t* rbt, walker_t walker, void* ctx)
 {
 	hawk_rbt_itr_t itr;
 	hawk_rbt_pair_t* pair;
 
-	itr._dir = 0;
+	hawk_init_map_itr (&itr, 0);
 	pair = hawk_rbt_getfirstpair(rbt, &itr);
 	while (pair)
 	{
@@ -1015,7 +1062,7 @@ void hawk_rbt_rwalk (hawk_rbt_t* rbt, walker_t walker, void* ctx)
 	hawk_rbt_itr_t itr;
 	hawk_rbt_pair_t* pair;
 
-	itr._dir = 1;
+	hawk_init_map_itr (&itr, 1);
 	pair = hawk_rbt_getfirstpair(rbt, &itr);
 	while (pair)
 	{
diff --git a/hawk/lib/run.c b/hawk/lib/run.c
index 85fdc758..cffde516 100644
--- a/hawk/lib/run.c
+++ b/hawk/lib/run.c
@@ -104,7 +104,7 @@ static int run_statement (hawk_rtx_t* rtx, hawk_nde_t* nde);
 static int run_if (hawk_rtx_t* rtx, hawk_nde_if_t* nde);
 static int run_while (hawk_rtx_t* rtx, hawk_nde_while_t* nde);
 static int run_for (hawk_rtx_t* rtx, hawk_nde_for_t* nde);
-static int run_foreach (hawk_rtx_t* rtx, hawk_nde_foreach_t* nde);
+static int run_forin (hawk_rtx_t* rtx, hawk_nde_forin_t* nde);
 static int run_break (hawk_rtx_t* rtx, hawk_nde_break_t* nde);
 static int run_continue (hawk_rtx_t* rtx, hawk_nde_continue_t* nde);
 static int run_return (hawk_rtx_t* rtx, hawk_nde_return_t* nde);
@@ -1136,6 +1136,17 @@ oops_0:
 
 static void fini_rtx (hawk_rtx_t* rtx, int fini_globals)
 {
+	if (rtx->forin.ptr)
+	{
+		while (rtx->forin.size > 0)
+		{
+			hawk_rtx_refdownval (rtx, rtx->forin.ptr[--rtx->forin.size]);
+		}
+		hawk_rtx_freemem (rtx, rtx->forin.ptr);
+		rtx->forin.ptr = HAWK_NULL;
+		rtx->forin.capa = 0;
+	}
+
 	if (rtx->pattern_range_state)
 		hawk_rtx_freemem (rtx, rtx->pattern_range_state);
 
@@ -1273,7 +1284,7 @@ static void fini_rtx (hawk_rtx_t* rtx, int fini_globals)
 		{
 			while (rtx->mbs_cache_count[i] > 0)
 			{
-				hawk_val_str_t* t = rtx->mbs_cache[i][--rtx->mbs_cache_count[i]];
+				hawk_val_mbs_t* t = rtx->mbs_cache[i][--rtx->mbs_cache_count[i]];
 				hawk_rtx_freeval (rtx, (hawk_val_t*)t, 0);
 			}
 		}
@@ -2154,7 +2165,7 @@ static HAWK_INLINE int run_block0 (hawk_rtx_t* rtx, hawk_nde_blk_t* nde)
 	while (nlcls > 0)
 	{
 		--nlcls;
-		hawk_rtx_refdownval (rtx, RTX_STACK_LCL(rtx,nlcls));
+		hawk_rtx_refdownval (rtx, RTX_STACK_LCL(rtx, nlcls));
 		__raw_pop (rtx);
 	}
 
@@ -2217,8 +2228,8 @@ static int run_statement (hawk_rtx_t* rtx, hawk_nde_t* nde)
 			xret = run_for(rtx, (hawk_nde_for_t*)nde);
 			break;
 
-		case HAWK_NDE_FOREACH:
-			xret = run_foreach(rtx, (hawk_nde_foreach_t*)nde);
+		case HAWK_NDE_FORIN:
+			xret = run_forin(rtx, (hawk_nde_forin_t*)nde);
 			break;
 
 		case HAWK_NDE_BREAK:
@@ -2476,15 +2487,17 @@ static int run_for (hawk_rtx_t* rtx, hawk_nde_for_t* nde)
 	return 0;
 }
 
-static int run_foreach (hawk_rtx_t* rtx, hawk_nde_foreach_t* nde)
+static int run_forin (hawk_rtx_t* rtx, hawk_nde_forin_t* nde)
 {
 	hawk_nde_exp_t* test;
 	hawk_val_t* rv;
-	hawk_map_t* map;
+	hawk_map_t* map = HAWK_NULL;
 	hawk_map_pair_t* pair;
 	hawk_map_itr_t itr;
 	hawk_val_type_t rvtype;
+	hawk_oow_t old_forin_size, i;
 	int ret;
+	
 
 	test = (hawk_nde_exp_t*)nde->test;
 	HAWK_ASSERT (test->type == HAWK_NDE_EXP_BIN && test->opcode == HAWK_BINOP_IN);
@@ -2514,12 +2527,94 @@ static int run_foreach (hawk_rtx_t* rtx, hawk_nde_foreach_t* nde)
 
 	map = ((hawk_val_map_t*)rv)->map;
 
+
+#if 1
+	old_forin_size = rtx->forin.size;
+
+	if (rtx->forin.capa - rtx->forin.size < hawk_map_getsize(map))
+	{
+		hawk_val_t** tmp;
+		hawk_oow_t newcapa;
+
+		newcapa = rtx->forin.size + hawk_map_getsize(map);
+		newcapa = HAWK_ALIGN_POW2(newcapa, 128);
+		tmp = hawk_rtx_reallocmem(rtx, rtx->forin.ptr, newcapa * HAWK_SIZEOF(*tmp));
+		if (HAWK_UNLIKELY(!tmp)) 
+		{
+			ADJERR_LOC (rtx, &test->left->loc);
+			ret = -1;
+			goto done;
+		}
+
+		rtx->forin.ptr = tmp;
+		rtx->forin.capa = newcapa;
+	}
+
+	/* take a snapshot of the keys first so that the actual pairs become mutation safe
+	 * this proctection is needed in case the body contains destructive statements like 'delete' or '@reset'*/
 	hawk_init_map_itr (&itr, 0);
 	pair = hawk_map_getfirstpair(map, &itr);
 	while (pair)
 	{
 		hawk_val_t* str;
 
+		str = (hawk_val_t*)hawk_rtx_makenstrvalwithoochars(rtx, HAWK_HTB_KPTR(pair), HAWK_HTB_KLEN(pair));
+		if (HAWK_UNLIKELY(!str)) 
+		{
+			ADJERR_LOC (rtx, &test->left->loc);
+			ret = -1;
+			goto done;
+		}
+
+		rtx->forin.ptr[rtx->forin.size++] = str;
+		hawk_rtx_refupval (rtx, str);
+
+		pair = hawk_map_getnextpair(map, &itr);
+	}
+
+	/* iterate over the keys in the snapshot */
+	for (i = old_forin_size;  i < rtx->forin.size; i++)
+	{
+		if (HAWK_UNLIKELY(!do_assignment(rtx, test->left, rtx->forin.ptr[i])) || HAWK_UNLIKELY(run_statement(rtx, nde->body) <= -1))
+		{
+			ret = -1;
+			goto done;
+		}
+
+		if (rtx->exit_level == EXIT_BREAK)
+		{
+			rtx->exit_level = EXIT_NONE;
+			goto done;
+		}
+		else if (rtx->exit_level == EXIT_CONTINUE)
+		{
+			rtx->exit_level = EXIT_NONE;
+		}
+		else if (rtx->exit_level != EXIT_NONE) 
+		{
+			goto done;
+		}
+	}
+
+done:
+	while (rtx->forin.size > old_forin_size)
+		hawk_rtx_refdownval (rtx, rtx->forin.ptr[--rtx->forin.size]);
+	hawk_rtx_refdownval (rtx, rv);
+	return ret;
+#else
+	hawk_init_map_itr (&itr, 0);
+#if defined(HAWK_MAP_IS_RBT)
+	hawk_rbt_protectitr (map, &itr);
+#endif
+	pair = hawk_map_getfirstpair(map, &itr);
+	while (pair)
+	{
+		hawk_val_t* str;
+
+#if defined(HAWK_MAP_IS_RBT)
+		itr._prot_updated = 0;
+#endif
+
 		str = (hawk_val_t*)hawk_rtx_makestrvalwithoochars(rtx, HAWK_HTB_KPTR(pair), HAWK_HTB_KLEN(pair));
 		if (HAWK_UNLIKELY(!str)) 
 		{
@@ -2529,7 +2624,7 @@ static int run_foreach (hawk_rtx_t* rtx, hawk_nde_foreach_t* nde)
 		}
 
 		hawk_rtx_refupval (rtx, str);
-		if (!do_assignment(rtx, test->left, str) || run_statement(rtx, nde->body) <= -1)
+		if (HAWK_UNLIKELY(!do_assignment(rtx, test->left, str)) || HAWK_UNLIKELY(run_statement(rtx, nde->body) <= -1))
 		{
 			hawk_rtx_refdownval (rtx, str);
 			ret = -1;
@@ -2551,12 +2646,20 @@ static int run_foreach (hawk_rtx_t* rtx, hawk_nde_foreach_t* nde)
 			goto done;
 		}
 
-		pair = hawk_map_getnextpair(map, &itr);
+#if defined(HAWK_MAP_IS_RBT)
+		pair = itr._prot_updated? itr.pair: hawk_map_getnextpair(map, &itr);
+#else
+#	error UNSUPPORTED
+#endif
 	}
 
 done:
+#if defined(HAWK_MAP_IS_RBT)
+	if (map) hawk_rbt_unprotectitr (map, &itr);
+#endif
 	hawk_rtx_refdownval (rtx, rv);
 	return ret;
+#endif
 }
 
 static int run_break (hawk_rtx_t* run, hawk_nde_break_t* nde)
diff --git a/hawk/lib/tree-prv.h b/hawk/lib/tree-prv.h
index f42e72a1..d9a2f519 100644
--- a/hawk/lib/tree-prv.h
+++ b/hawk/lib/tree-prv.h
@@ -71,7 +71,7 @@ typedef struct hawk_nde_getline_t   hawk_nde_getline_t;
 typedef struct hawk_nde_if_t        hawk_nde_if_t;
 typedef struct hawk_nde_while_t     hawk_nde_while_t;
 typedef struct hawk_nde_for_t       hawk_nde_for_t;
-typedef struct hawk_nde_foreach_t   hawk_nde_foreach_t;
+typedef struct hawk_nde_forin_t   hawk_nde_forin_t;
 typedef struct hawk_nde_break_t     hawk_nde_break_t;
 typedef struct hawk_nde_continue_t  hawk_nde_continue_t;
 typedef struct hawk_nde_return_t    hawk_nde_return_t;
@@ -263,8 +263,8 @@ struct hawk_nde_for_t
 	hawk_nde_t* body;
 };
 
-/* HAWK_NDE_FOREACH */
-struct hawk_nde_foreach_t
+/* HAWK_NDE_FORIN */
+struct hawk_nde_forin_t
 {
 	HAWK_NDE_HDR;
 	hawk_nde_t* test;
diff --git a/hawk/lib/tree.c b/hawk/lib/tree.c
index 883c1a60..c1572d2c 100644
--- a/hawk/lib/tree.c
+++ b/hawk/lib/tree.c
@@ -955,9 +955,9 @@ static int print_stmt (hawk_t* awk, hawk_nde_t* p, int depth)
 			break;
 		}
 
-		case HAWK_NDE_FOREACH:
+		case HAWK_NDE_FORIN:
 		{
-			hawk_nde_foreach_t* px = (hawk_nde_foreach_t*)p;
+			hawk_nde_forin_t* px = (hawk_nde_forin_t*)p;
 
 			PRINT_TABS (awk, depth);
 			hawk_getkwname (awk, HAWK_KWID_FOR, &kw);
@@ -1209,10 +1209,10 @@ void hawk_clrpt (hawk_t* awk, hawk_nde_t* tree)
 				break;
 			}
 
-			case HAWK_NDE_FOREACH:
+			case HAWK_NDE_FORIN:
 			{
-				hawk_clrpt (awk, ((hawk_nde_foreach_t*)p)->test);
-				hawk_clrpt (awk, ((hawk_nde_foreach_t*)p)->body);
+				hawk_clrpt (awk, ((hawk_nde_forin_t*)p)->test);
+				hawk_clrpt (awk, ((hawk_nde_forin_t*)p)->body);
 				hawk_freemem (awk, p);
 				break;
 			}
diff --git a/hawk/lib/val.c b/hawk/lib/val.c
index f278a052..b010c9d8 100644
--- a/hawk/lib/val.c
+++ b/hawk/lib/val.c
@@ -127,7 +127,7 @@ static void gc_trace_refs (hawk_gch_t* list)
 
 		/* as of now, there is only one type available - HAWK_VAL_MAP */
 		HAWK_ASSERT (v->v_type == HAWK_VAL_MAP);
-		itr._dir = 0;
+		hawk_init_map_itr (&itr, 0);
 		pair = hawk_map_getfirstpair(((hawk_val_map_t*)v)->map, &itr);
 		while (pair)
 		{
@@ -184,7 +184,7 @@ static void gc_move_reachables (hawk_gch_t* list, hawk_gch_t* reachable_list)
 		/* as of now, there is only one type available - HAWK_VAL_MAP */
 /* the key part is a string. don't care. but if a generic value is allowed as a key, this should change... */
 		HAWK_ASSERT (v->v_type == HAWK_VAL_MAP);
-		itr._dir = 0;
+		hawk_init_map_itr (&itr, 0);
 		pair = hawk_map_getfirstpair(((hawk_val_map_t*)v)->map, &itr);
 		while (pair)
 		{
@@ -214,8 +214,29 @@ static void gc_free_unreachables (hawk_rtx_t* rtx, hawk_gch_t* list)
 	while (gch != list)
 	{
 		tmp = gch->gc_next;
-printf ("^^^^^^^^^^^^^^^^^^^^^^^^ freeing %p(%p)    gc_refs %d v_refs %d\n", gch, gch->gc_refs, hawk_gch_to_val(gch)->v_refs);
-		hawk_rtx_freeval (rtx, hawk_gch_to_val(gch), 0);
+
+printf ("^^^^^^^^^^^^^^^^^^^^^^^^ freeing %p    gc_refs %d v_refs %d\n", gch, (int)gch->gc_refs, (int)hawk_gch_to_val(gch)->v_refs);
+		//hawk_rtx_freeval (rtx, hawk_gch_to_val(gch), 0);
+
+		{
+			// TODO: revise this. MAP ONLY as of now.
+			hawk_val_map_t* v = (hawk_val_map_t*)hawk_gch_to_val(gch);
+			hawk_map_pair_t* pair;
+			hawk_map_itr_t itr;
+			hawk_oow_t refs = 0;
+
+			hawk_init_map_itr (&itr, 0);
+			pair = hawk_map_getfirstpair(v->map, &itr);
+			while (pair)
+			{
+				if (HAWK_MAP_VPTR(pair) == v) refs++;
+				else hawk_rtx_refdownval (rtx, HAWK_MAP_VPTR(pair));
+				pair = hawk_map_getnextpair(v->map, &itr);
+			}
+
+			while (refs-- > 0) hawk_rtx_refdownval (rtx, v);
+		}
+
 		gch = tmp;
 	}
 }
@@ -234,6 +255,7 @@ printf ("collecting garbage...\n");
 	/* only unreachables are left in rtx->gc.all */
 gc_dump_refs (rtx, &rtx->gc.all);
 	gc_free_unreachables (rtx, &rtx->gc.all);
+gc_dump_refs (rtx, &rtx->gc.all);
 	HAWK_ASSERT (rtx->gc.all.gc_next == &rtx->gc.all); 
 
 	gc_move_gchs (&rtx->gc.all, &reachable);
@@ -534,6 +556,7 @@ hawk_val_t* hawk_rtx_makenstrvalwithuchars (hawk_rtx_t* rtx, const hawk_uch_t* p
 	v = hawk_rtx_makestrvalwithuchars(rtx, ptr, len);
 	if (HAWK_UNLIKELY(!v)) return HAWK_NULL;
 
+
 	if (x >= 0) 
 	{
 		/* set the numeric string flag if a string