diff --git a/system_files/shared/usr/libexec/sb-key-notify.sh b/system_files/shared/usr/libexec/sb-key-notify.sh
index e5ef6c1055e..db21221f66a 100644
--- a/system_files/shared/usr/libexec/sb-key-notify.sh
+++ b/system_files/shared/usr/libexec/sb-key-notify.sh
@@ -21,7 +21,7 @@ if mokutil --test-key "$KEY_DER_FILE"; then
     if loginctl --help | grep -q "json=MODE"; then
         JSON_ARG="--json=short"
     fi
-    USER_ID=$(loginctl list-users --output=json "$JSON_ARG" | jq -r '.[] | .user')
+    USER_ID=$(loginctl list-users --output=json ${JSON_ARG:+$JSON_ARG} | jq -r '.[] | .user')
     XDG_DIR=$(loginctl show-user "$USER_ID" | grep RuntimePath | cut -c 13-)
     sudo -u "$USER_ID" \
         "DISPLAY=:0" \