--- gawk-3.1.5/builtin.c.orig	2006-12-17 23:51:38 +0000
+++ gawk-3.1.5/builtin.c	2006-12-17 23:56:58 +0000
@@ -2020,7 +2020,7 @@ do_match(NODE *tree)
 
 		rlength = REEND(rp, t1->stptr) - RESTART(rp, t1->stptr);	/* byte length */
 #ifdef MBS_SUPPORT
-		if (gawk_mb_cur_max > 1) {
+		if (rlength > 0 && gawk_mb_cur_max > 1) {
 			t1 = str2wstr(t1, & wc_indices);
 			rlength = wc_indices[rstart + rlength - 1] - wc_indices[rstart] + 1;
 			rstart = wc_indices[rstart];
@@ -2046,7 +2046,7 @@ do_match(NODE *tree)
 					subpat_start = s;
 					subpat_len = len = SUBPATEND(rp, t1->stptr, ii) - s;
 #ifdef MBS_SUPPORT
-					if (gawk_mb_cur_max > 1) {
+					if (len > 0 && gawk_mb_cur_max > 1) {
 						subpat_start = wc_indices[s];
 						subpat_len = wc_indices[s + len - 1] - subpat_start + 1;
 					}