diff --git a/ChangeLog b/ChangeLog
index cc6ada37..2dec521b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-27  Even Rouault  <even.rouault@spatialys.com>
+
+	* libtiff/tif_dir.c: in TIFFDefaultDirectory(), reset any already existing
+	extented tags installed by user code through the extender mechaninm before
+	calling the extender callback (GDAL #5054)
+
 2014-12-26  Bob Friesenhahn  <bfriesen@simple.dallas.tx.us>
 
 	* tools/tiffcrop.c: Fix warnings about variables set but not used.
diff --git a/libtiff/tif_dir.c b/libtiff/tif_dir.c
index daead652..17bf8782 100644
--- a/libtiff/tif_dir.c
+++ b/libtiff/tif_dir.c
@@ -1,4 +1,4 @@
-/* $Id: tif_dir.c,v 1.118 2014-12-21 15:15:31 erouault Exp $ */
+/* $Id: tif_dir.c,v 1.119 2014-12-27 15:20:42 erouault Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -1322,8 +1322,20 @@ TIFFDefaultDirectory(TIFF* tif)
 	tif->tif_tagmethods.printdir = NULL;
 	/*
 	 *  Give client code a chance to install their own
-	 *  tag extensions & methods, prior to compression overloads.
+	 *  tag extensions & methods, prior to compression overloads,
+	 *  but do some prior cleanup first. (http://trac.osgeo.org/gdal/ticket/5054)
 	 */
+	if (tif->tif_nfieldscompat > 0) {
+		uint32 i;
+
+		for (i = 0; i < tif->tif_nfieldscompat; i++) {
+				if (tif->tif_fieldscompat[i].allocated_size)
+						_TIFFfree(tif->tif_fieldscompat[i].fields);
+		}
+		_TIFFfree(tif->tif_fieldscompat);
+		tif->tif_nfieldscompat = 0;
+		tif->tif_fieldscompat = NULL;
+	}
 	if (_TIFFextender)
 		(*_TIFFextender)(tif);
 	(void) TIFFSetField(tif, TIFFTAG_COMPRESSION, COMPRESSION_NONE);