===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/m4/eval.c,v
retrieving revision 1.66
retrieving revision 1.67
diff -u -r1.66 -r1.67
--- src/usr.bin/m4/eval.c	2008/08/21 21:01:47	1.66
+++ src/usr.bin/m4/eval.c	2010/03/25 18:52:29	1.67
@@ -1,4 +1,4 @@
-/*	$OpenBSD: eval.c,v 1.66 2008/08/21 21:01:47 espie Exp $	*/
+/*	$OpenBSD: eval.c,v 1.67 2010/03/25 18:52:29 espie Exp $	*/
 /*	$NetBSD: eval.c,v 1.7 1996/11/10 21:21:29 pk Exp $	*/
 
 /*
@@ -907,6 +907,8 @@
 	unsigned char sch, dch;
 	static char frombis[257];
 	static char tobis[257];
+	int i;
+	char seen[256];
 	static unsigned char mapvec[256] = {
 	    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
 	    19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
@@ -941,9 +943,17 @@
 	 * create a mapping between "from" and
 	 * "to"
 	 */
-		while (*from)
-			mapvec[(unsigned char)(*from++)] = (*to) ? 
-				(unsigned char)(*to++) : 0;
+		for (i = 0; i < 256; i++)
+			seen[i] = 0;
+		while (*from) {
+			if (!seen[(unsigned char)(*from)]) {
+				mapvec[(unsigned char)(*from)] = (unsigned char)(*to);
+				seen[(unsigned char)(*from)] = 1;
+			}
+			from++;
+			if (*to)
+				to++;
+		}
 
 		while (*src) {
 			sch = (unsigned char)(*src++);