diff --git a/docker/mqtt.sh b/docker/mqtt.sh
index 720366d..4cdef70 100644
--- a/docker/mqtt.sh
+++ b/docker/mqtt.sh
@@ -116,8 +116,22 @@ while true; do
     # sleep first to avoid publishing zeroes on first iteration
     sleep "$MQTT_PAUSE"
 
-    # output a single line to mosquitto_pub
-    (/app/orb summary || echo '{}') | jq -c .
+    # output a single line to mosquitto_pub. orb summary prints a startup
+    # banner to stderr on every invocation, which would flood the journal at
+    # MQTT_PAUSE cadence -- so capture stderr in a variable (fd 3 carries the
+    # real stdout out of the command substitution) and only replay it when
+    # orb fails (it's the only diagnostic we have then) or mqtt_debug is on.
+    {
+      ORB_ERRS=$(/app/orb summary 2>&1 >&3)
+      ORB_RC=$?
+      if [ "$ORB_RC" -ne 0 ]; then
+        echo "orb summary failed (exit $ORB_RC):" >&2
+        [ -n "$ORB_ERRS" ] && printf '%s\n' "$ORB_ERRS" >&2
+        echo '{}'
+      elif [ "$DEBUG_MODE" = "true" ] && [ -n "$ORB_ERRS" ]; then
+        printf '%s\n' "$ORB_ERRS" >&2
+      fi
+    } 3>&1 | jq -c .
 
   done | mosquitto_pub -h "$MQTT_HOST" -p "$MQTT_PORT" -u "$MQTT_USER" -P "$MQTT_PASS" \
     -t "$STATE_TOPIC" -l -r -k $((MQTT_PAUSE * 2))