defer creation of locking model to ActivateOptions
diff --git a/src/log4net/Appender/FileAppender.cs b/src/log4net/Appender/FileAppender.cs
index bf78271..af0b387 100644
--- a/src/log4net/Appender/FileAppender.cs
+++ b/src/log4net/Appender/FileAppender.cs
@@ -1657,7 +1657,7 @@
         /// <summary>
         /// The locking model to use
         /// </summary>
-        private FileAppender.LockingModelBase m_lockingModel = new FileAppender.ExclusiveLock();
+        private FileAppender.LockingModelBase m_lockingModel;
 
         #endregion Private Instance Fields