diff --git a/test/units/TEST-54-CREDS.sh b/test/units/TEST-54-CREDS.sh
index b549745e0d..75332892f9 100755
--- a/test/units/TEST-54-CREDS.sh
+++ b/test/units/TEST-54-CREDS.sh
@@ -482,11 +482,25 @@ fi
 
 # Decrypt/encrypt via varlink
 
-echo '{"data":"Zm9vYmFyCg=="}' > /tmp/vlcredsdata
+DATA="Zm9vYmFyCg=="
+echo "{\"data\":\"$DATA\"}" > /tmp/vlcredsdata
 
 varlinkctl call /run/systemd/io.systemd.Credentials io.systemd.Credentials.Encrypt "$(cat /tmp/vlcredsdata)" | \
     varlinkctl call --json=short /run/systemd/io.systemd.Credentials io.systemd.Credentials.Decrypt > /tmp/vlcredsdata2
 
+cmp /tmp/vlcredsdata /tmp/vlcredsdata2
+rm /tmp/vlcredsdata2
+
+# Pick a key type explicitly
+varlinkctl call /run/systemd/io.systemd.Credentials io.systemd.Credentials.Encrypt "{\"data\":\"$DATA\",\"withKey\":\"host\"}" | \
+    varlinkctl call --json=short /run/systemd/io.systemd.Credentials io.systemd.Credentials.Decrypt > /tmp/vlcredsdata2
+
+cmp /tmp/vlcredsdata /tmp/vlcredsdata2
+rm /tmp/vlcredsdata2
+
+varlinkctl call /run/systemd/io.systemd.Credentials io.systemd.Credentials.Encrypt "{\"data\":\"$DATA\",\"withKey\":\"null\"}" | \
+    varlinkctl call --json=short /run/systemd/io.systemd.Credentials io.systemd.Credentials.Decrypt > /tmp/vlcredsdata2
+
 cmp /tmp/vlcredsdata /tmp/vlcredsdata2
 rm /tmp/vlcredsdata /tmp/vlcredsdata2