diff --git a/smallrye-reactive-messaging-mqtt/src/main/java/io/smallrye/reactive/messaging/mqtt/MqttSource.java b/smallrye-reactive-messaging-mqtt/src/main/java/io/smallrye/reactive/messaging/mqtt/MqttSource.java
index aa9d3121a..fb4c33bfe 100644
--- a/smallrye-reactive-messaging-mqtt/src/main/java/io/smallrye/reactive/messaging/mqtt/MqttSource.java
+++ b/smallrye-reactive-messaging-mqtt/src/main/java/io/smallrye/reactive/messaging/mqtt/MqttSource.java
@@ -70,6 +70,7 @@ public MqttSource(Vertx vertx, MqttConnectorIncomingConfiguration config,
 
         this.source = holder.stream()
                 .select().where(m -> MqttTopicHelper.matches(topic, pattern, m))
+                .onOverflow().buffer(config.getBufferSize())
                 .emitOn(c -> VertxContext.runOnContext(root.getDelegate(), c))
                 .onItem().transform(m -> new ReceivingMqttMessage(m, onNack))
                 .stage(multi -> {
@@ -78,7 +79,6 @@ public MqttSource(Vertx vertx, MqttConnectorIncomingConfiguration config,
 
                     return multi;
                 })
-                .onOverflow().buffer(config.getBufferSize())
                 .onCancellation().call(() -> {
                     alive.set(false);
                     if (config.getUnsubscribeOnDisconnection())
diff --git a/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQTest.java b/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQTest.java
index b4379bfe2..b79c77c99 100644
--- a/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQTest.java
+++ b/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQTest.java
@@ -11,7 +11,6 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
 
-import io.smallrye.common.annotation.CheckReturnValue;
 import jakarta.enterprise.context.ApplicationScoped;
 
 import org.eclipse.microprofile.config.ConfigProvider;
@@ -476,7 +475,6 @@ static class DeliveryTagInterceptor implements OutgoingInterceptor {
 
         List<Long> deliveryTagsNack = new CopyOnWriteArrayList<>();
 
-
         @Override
         public void onMessageAck(Message<?> message) {
             message.getMetadata(OutgoingMessageMetadata.class).ifPresent(m -> deliveryTags.add((long) m.getResult()));
@@ -484,7 +482,8 @@ public void onMessageAck(Message<?> message) {
 
         @Override
         public void onMessageNack(Message<?> message, Throwable failure) {
-            message.getMetadata(OutgoingMessageMetadata.class).ifPresent(m -> deliveryTagsNack.add(((Integer) message.getPayload()).longValue()));
+            message.getMetadata(OutgoingMessageMetadata.class)
+                    .ifPresent(m -> deliveryTagsNack.add(((Integer) message.getPayload()).longValue()));
         }
 
         public List<Long> getDeliveryTags() {
@@ -495,7 +494,7 @@ public List<Long> getDeliveryTagsNack() {
             return deliveryTagsNack;
         }
 
-        public int numberOfProcessedMessage(){
+        public int numberOfProcessedMessage() {
             return deliveryTags.size() + deliveryTagsNack.size();
         }
     }
@@ -511,10 +510,12 @@ void testSendingMessagesToRabbitMQPublishConfirmsWithNack() throws InterruptedEx
 
         List<Long> receivedTags = new CopyOnWriteArrayList<>();
         CountDownLatch latch = new CountDownLatch(10);
-        usage.prepareNackQueue(exchangeName, routingKey);/*, v -> {
-            receivedTags.add(v.envelope().getDeliveryTag());
-            latch.countDown();
-        });*/
+        usage.prepareNackQueue(exchangeName, routingKey);/*
+                                                          * , v -> {
+                                                          * receivedTags.add(v.envelope().getDeliveryTag());
+                                                          * latch.countDown();
+                                                          * });
+                                                          */
 
         weld.addBeanClasses(ProducingBean.class, DeliveryTagInterceptor.class);
 
@@ -536,21 +537,15 @@ void testSendingMessagesToRabbitMQPublishConfirmsWithNack() throws InterruptedEx
         await().until(() -> isRabbitMQConnectorAvailable(container));
 
         DeliveryTagInterceptor interceptor = get(container, DeliveryTagInterceptor.class);
-        await().until(() ->
-                interceptor.numberOfProcessedMessage() == 10);
-
-
+        await().until(() -> interceptor.numberOfProcessedMessage() == 10);
 
         assertThat(interceptor.getDeliveryTags())
-                .hasSizeBetween(1,2);
+                .hasSizeBetween(1, 2);
 
         assertThat(interceptor.getDeliveryTagsNack())
-                .hasSizeBetween(8,9);
+                .hasSizeBetween(8, 9);
     }
 
-
-
-
     /**
      * Verifies that messages can be sent to RabbitMQ.
      *
diff --git a/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQUsage.java b/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQUsage.java
index e467886ec..d98fa691f 100644
--- a/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQUsage.java
+++ b/smallrye-reactive-messaging-rabbitmq/src/test/java/io/smallrye/reactive/messaging/rabbitmq/RabbitMQUsage.java
@@ -25,14 +25,12 @@
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
-import io.smallrye.common.annotation.CheckReturnValue;
-import io.smallrye.mutiny.Uni;
-import io.vertx.core.Future;
 import org.jboss.logging.Logger;
 
 import com.rabbitmq.client.AMQP;
 import com.rabbitmq.client.BasicProperties;
 
+import io.smallrye.common.annotation.CheckReturnValue;
 import io.vertx.core.json.JsonArray;
 import io.vertx.core.json.JsonObject;
 import io.vertx.mutiny.core.Vertx;
@@ -180,15 +178,16 @@ public void prepareNackQueue(String exchange, String routingKey) {
 
         client.queueBindAndAwait(queue, exchange, routingKey);
 
-
     }
 
-    public com.rabbitmq.client.AMQP.Queue.DeclareOk queueDeclareAndAwait(String queue, boolean durable, boolean exclusive, boolean autoDelete, JsonObject config) {
-        return (com.rabbitmq.client.AMQP.Queue.DeclareOk) queueDeclare(queue, durable, exclusive, autoDelete, config).await().indefinitely();
+    public com.rabbitmq.client.AMQP.Queue.DeclareOk queueDeclareAndAwait(String queue, boolean durable, boolean exclusive,
+            boolean autoDelete, JsonObject config) {
+        return queueDeclare(queue, durable, exclusive, autoDelete, config).await().indefinitely();
     }
 
     @CheckReturnValue
-    public io.smallrye.mutiny.Uni<com.rabbitmq.client.AMQP.Queue.DeclareOk> queueDeclare(String queue, boolean durable, boolean exclusive, boolean autoDelete,JsonObject config) {
+    public io.smallrye.mutiny.Uni<com.rabbitmq.client.AMQP.Queue.DeclareOk> queueDeclare(String queue, boolean durable,
+            boolean exclusive, boolean autoDelete, JsonObject config) {
         return io.smallrye.mutiny.vertx.AsyncResultUni.toUni(resultHandler -> {
             client.getDelegate().queueDeclare(queue, durable, exclusive, autoDelete, config, resultHandler);
         });