diff --git a/drb-c2-core/mosquitto/entrypoint.sh b/drb-c2-core/mosquitto/entrypoint.sh
index 27d17ce..a3f9035 100644
--- a/drb-c2-core/mosquitto/entrypoint.sh
+++ b/drb-c2-core/mosquitto/entrypoint.sh
@@ -24,8 +24,9 @@ if [ -z "$MQTT_NODE_USER" ] || [ -z "$MQTT_NODE_PASS" ]; then
     exit 1
 fi
 
-mosquitto_passwd -b "$PASSWD_FILE" "$MQTT_C2_USER"   "$MQTT_C2_PASS"
-mosquitto_passwd -b "$PASSWD_FILE" "$MQTT_NODE_USER" "$MQTT_NODE_PASS"
+# -c creates/overwrites the file; subsequent calls append without -c
+mosquitto_passwd -c -b "$PASSWD_FILE" "$MQTT_C2_USER"   "$MQTT_C2_PASS"
+mosquitto_passwd    -b "$PASSWD_FILE" "$MQTT_NODE_USER" "$MQTT_NODE_PASS"
 
 echo "Mosquitto: password file written for users: $MQTT_C2_USER, $MQTT_NODE_USER"