diff --git a/test/units/testsuite-04.sh b/test/units/testsuite-04.sh
index 6e7627313c..df216a06a3 100755
--- a/test/units/testsuite-04.sh
+++ b/test/units/testsuite-04.sh
@@ -87,6 +87,14 @@ journalctl -b -o export -t "$ID" --output-fields=_PID | grep '^_PID=' >/output
 grep -q "^_PID=$PID" /output
 grep -vq "^_PID=$PID" /output
 
+# https://github.com/systemd/systemd/issues/15654
+ID=$(journalctl --new-id128 | sed -n 2p)
+printf "This will\nusually fail\nand be truncated\n">/expected
+systemd-cat -t "$ID" /bin/sh -c 'env echo -n "This will";echo;env echo -n "usually fail";echo;env echo -n "and be truncated";echo;'
+journalctl --sync
+journalctl -b -o cat -t "$ID" >/output
+cmp /expected /output
+
 # Add new tests before here, the journald restarts below
 # may make tests flappy.