I wish. But '1#\xC2\x0A' converts correctly, as the newline isn't seen…

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.182 2008/04/20 00:28:30 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.183 2008/04/20 00:45:49 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -4812,6 +4812,10 @@ stdin:
 			print -n "\u${i#16#1}"
 		done
 		print
+		print \\xff		# invalid utf-8
+		print \\xc2		# invalid 2-byte
+		print \\xef\\xbf\\x80	# invalid 3-byte
+		print \\xc2\\x80	# non-minimalistic
 	} | {
 		typeset -Uui16 -Z11 pos=0
 		typeset -Uui16 -Z5 hv
@@ -4822,17 +4826,23 @@ stdin:
 		while IFS= read -r line; do
 			line=$line$nl
 			while [[ -n $line ]]; do
-				if (integer x=1#${line::3}) 2>&-; then
-					n=3
-				elif (integer x=1#${line::2}) 2>&-; then
+				(( hv = 1#${line::1} & 0xFF ))
+				if (( (hv < 0xC2) || (hv >= 0xF0) )); then
+					n=1
+				elif (( hv < 0xE0 )); then
 					n=2
 				else
-					n=1
+					n=3
 				fi
+	(( n == 1 )) || eval integer 'x=1#${line::n}' 2>/dev/null || print -u2 on 1#${line::n}
+				(( n == 1 )) || \
+				    (integer x=1#${line::n}) 2>/dev/null || n=1
 				wc=1#${line::n}
 				if (( (wc < 32) || \
 				    ((wc > 126) && (wc < 160)) )); then
 					dch=.
+				elif (( (wc & 0xFF80) == 0xEF80 )); then
+					dch=<EFBFBD>
 				else
 					dch=${wc#1#}
 				fi
@@ -4890,5 +4900,5 @@ expected-stdout:
 	00000170  A7 C3 A8 C3 A9 C3 AA C3 - AB C3 AC C3 AD C3 AE C3  |èéêëìíîï|
 	00000180  AF C3 B0 C3 B1 C3 B2 C3 - B3 C3 B4 C3 B5 C3 B6 C3  |ðñòóôõö÷|
 	00000190  B7 C3 B8 C3 B9 C3 BA C3 - BB C3 BC C3 BD C3 BE C3  |øùúûüýþÿ|
-	000001A0  BF 0A                   -                          |.|
+	000001A0  BF 0A FF 0A C2 0A EF BF - 80 0A C2 80 0A           |.<EFBFBD>.<EFBFBD>.<EFBFBD><EFBFBD>.<EFBFBD><EFBFBD>.|
 ---