--- a/tests/wdiff.at
+++ b/tests/wdiff.at
@@ -173,7 +173,7 @@
 # Due to the istty call in the sources, we have to use screen here.
 
 LC_ALL=C
-AT_TESTED([wdiff diff screen env sed grep])
+AT_TESTED([wdiff diff screen env sed tr grep])
 AT_DATA([foo.txt], [start foo end
 ])
 AT_DATA([bar.txt], [start bar end
@@ -193,7 +193,7 @@
 AT_SKIP_IF([grep 'terminal type.*not defined' screenlog.0])
 # Need to work around a screen bug which might cause the first
 # character to be lost: https://savannah.gnu.org/bugs/index.php?34200
-AT_CHECK([sed 's/^ager/Pager/;s/\r//g;' screenlog.0], 0,
+AT_CHECK([tr -d '\r' < screenlog.0 | sed 's/^ager/Pager/'], 0,
 [Pager starting.
 Pager line start WfooX YbarZ end printed.
 Pager now done.
--- a/tests/testsuite
+++ b/tests/testsuite
@@ -593,7 +593,8 @@
 grep
 diff
 screen
-sed'
+sed
+tr'
 # As many question marks as there are digits in the last test group number.
 # Used to normalize the test group numbers so that `ls' lists them in
 # numerical order.
@@ -2380,9 +2381,9 @@
 # Need to work around a screen bug which might cause the first
 # character to be lost: https://savannah.gnu.org/bugs/index.php?34200
 { set +x
-$as_echo "$at_srcdir/wdiff.at:196: sed 's/^ager/Pager/;s/\\r//g;' screenlog.0"
-at_fn_check_prepare_trace "wdiff.at:196"
-( $at_check_trace; sed 's/^ager/Pager/;s/\r//g;' screenlog.0
+$as_echo "$at_srcdir/wdiff.at:196: tr -d '\\r' < screenlog.0 | sed 's/^ager/Pager/'"
+at_fn_check_prepare_notrace 'a shell pipeline' "wdiff.at:196"
+( $at_check_trace; tr -d '\r' < screenlog.0 | sed 's/^ager/Pager/'
 ) >>"$at_stdout" 2>>"$at_stderr"
 at_status=$? at_failed=false
 $at_check_filter