:sparkles: make it obvious that the derived appender is being used
diff --git a/src/integration-testing/log4net-611-lib/DerivedAppender.cs b/src/integration-testing/log4net-611-lib/DerivedAppender.cs
index a22b426..2b1faeb 100644
--- a/src/integration-testing/log4net-611-lib/DerivedAppender.cs
+++ b/src/integration-testing/log4net-611-lib/DerivedAppender.cs
@@ -1,8 +1,14 @@
 using log4net.Appender;
+using log4net.Core;
 using log4net.Layout;
 
 namespace log4net_611_lib;
 
 public class DerivedAppender: RollingFileAppender
 {
+    protected override void Append(LoggingEvent loggingEvent)
+    {
+        loggingEvent.Properties["appender-class-name"] = nameof(DerivedAppender);
+        base.Append(loggingEvent);
+    }
 }
\ No newline at end of file
diff --git a/src/integration-testing/log4net-611-main/log4net.config b/src/integration-testing/log4net-611-main/log4net.config
index 77e850b..5b44409 100644
--- a/src/integration-testing/log4net-611-main/log4net.config
+++ b/src/integration-testing/log4net-611-main/log4net.config
@@ -10,7 +10,7 @@
     <preserveLogFileNameExtension value="true" />
     <staticLogFileName value="false" />
     <layout type="log4net.Layout.PatternLayout">
-      <conversionPattern value="[file] %message%newline" />
+      <conversionPattern value="[file] %property{appender-class-name} %message%newline" />
     </layout>
     <immediateFlush value="true" />
   </appender>