Index: pbx.c
===================================================================
--- pbx.c	(revision 13633)
+++ pbx.c	(working copy)
@@ -3728,9 +3728,11 @@
 	}
 	/* Fill the mask. Remember that ranges are cyclic */
 	mask = 1 << e;	/* initialize with last element */
-	for ( ; s != e; s++) {
-		if (s == max)
-			s = 0 ;
+	while (s != e) {
+		if (s >= max)
+			s = 0;
+		else
+			s++;
 		mask |= (1 << s);
 	}
 	return mask;