===================================================================
RCS file: /cvs/mandoc/roff.c,v
retrieving revision 1.353
retrieving revision 1.354
diff -u -p -r1.353 -r1.354
--- mandoc/roff.c	2018/12/18 22:00:02	1.353
+++ mandoc/roff.c	2018/12/20 03:41:54	1.354
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.353 2018/12/18 22:00:02 schwarze Exp $ */
+/*	$Id: roff.c,v 1.354 2018/12/20 03:41:54 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -1588,7 +1588,7 @@ mandoc_getarg(char **cpp, int ln, int *pos)
 			switch (cp[1]) {
 			case 'a':
 			case 't':
-				cp[0] = '\t';
+				cp[-pairs] = '\t';
 				/* FALLTHROUGH */
 			case '\\':
 				pairs++;