diff --git a/include/mqtt_config.h b/include/mqtt_config.h
index e259a2a..d9b64c7 100644
--- a/include/mqtt_config.h
+++ b/include/mqtt_config.h
@@ -84,8 +84,8 @@
 #endif
 #endif
 
-#ifdef  CONFIG_OUTBOX_EXPIRED_TIMEOUT_MS
-#define OUTBOX_EXPIRED_TIMEOUT_MS   CONFIG_OUTBOX_EXPIRED_TIMEOUT_MS
+#ifdef  CONFIG_MQTT_OUTBOX_EXPIRED_TIMEOUT_MS
+#define OUTBOX_EXPIRED_TIMEOUT_MS   CONFIG_MQTT_OUTBOX_EXPIRED_TIMEOUT_MS
 #else
 #define OUTBOX_EXPIRED_TIMEOUT_MS   (30*1000)
 #endif