diff --git a/src/NServiceBus.Transport.RabbitMQ/Receiving/MessagePump.cs b/src/NServiceBus.Transport.RabbitMQ/Receiving/MessagePump.cs
index 5dde3fcf7..73e19b74a 100644
--- a/src/NServiceBus.Transport.RabbitMQ/Receiving/MessagePump.cs
+++ b/src/NServiceBus.Transport.RabbitMQ/Receiving/MessagePump.cs
@@ -28,8 +28,8 @@ sealed class MessagePump : IMessageReceiver, IDisposable
         readonly Action<string, Exception, CancellationToken> criticalErrorAction;
         readonly TimeSpan retryDelay;
         readonly string name;
-        readonly FastConcurrentLru<string, int> deliveryAttempts = new(100);
-        readonly FastConcurrentLru<string, bool> failedBasicAckMessages = new(100);
+        readonly FastConcurrentLru<string, int> deliveryAttempts = new(1_000);
+        readonly FastConcurrentLru<string, bool> failedBasicAckMessages = new(1_000);
 
         bool disposed;
         OnMessage onMessage;
@@ -531,4 +531,4 @@ public void Dispose()
             disposed = true;
         }
     }
-}
+}
\ No newline at end of file