diff --git a/broker/src/main/java/io/moquette/spi/impl/ProtocolProcessor.java b/broker/src/main/java/io/moquette/spi/impl/ProtocolProcessor.java
index f83ead51..7b71cbb3 100644
--- a/broker/src/main/java/io/moquette/spi/impl/ProtocolProcessor.java
+++ b/broker/src/main/java/io/moquette/spi/impl/ProtocolProcessor.java
@@ -844,7 +844,7 @@ public class ProtocolProcessor {
             grantedQoSLevels.add(req.qualityOfService().value());
         }
 
-        MqttFixedHeader fixedHeader = new MqttFixedHeader(MqttMessageType.SUBACK, false, AT_LEAST_ONCE, false, 0);
+        MqttFixedHeader fixedHeader = new MqttFixedHeader(MqttMessageType.SUBACK, false, AT_MOST_ONCE, false, 0);
         MqttSubAckPayload payload = new MqttSubAckPayload(grantedQoSLevels);
         return new MqttSubAckMessage(fixedHeader, from(messageId), payload);
     }