diff --git a/ChangeLog b/ChangeLog
index fe756341..167fa461 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2010-04-21  Frank Warmerdam  <warmerdam@pobox.com>
+
+	* libtiff/tif_jpeg.c: avoid preparing jpeg tables everytime 
+	JPEGSetupEncode() is called if the tables already seem to be 
+	established.  This prevents spurious updates and rewriting of 
+	directories with jpegtables when doing updates to existing images.
+	http://trac.osgeo.org/gdal/ticket/3539
+
 2010-04-20  Olivier Paquet  <olivier.paquet@gmail.com>
 
 	* libtiff/tif_dirinfo.c: Use correct set_field_type for
diff --git a/libtiff/tif_jpeg.c b/libtiff/tif_jpeg.c
index d7cb5862..feba186e 100644
--- a/libtiff/tif_jpeg.c
+++ b/libtiff/tif_jpeg.c
@@ -1,4 +1,4 @@
-/* $Id: tif_jpeg.c,v 1.88 2010-03-10 18:56:48 bfriesen Exp $ */
+/* $Id: tif_jpeg.c,v 1.89 2010-04-21 20:46:17 fwarmerdam Exp $ */
 
 /*
  * Copyright (c) 1994-1997 Sam Leffler
@@ -1612,12 +1612,16 @@ JPEGSetupEncode(TIFF* tif)
 
 	/* Create a JPEGTables field if appropriate */
 	if (sp->jpegtablesmode & (JPEGTABLESMODE_QUANT|JPEGTABLESMODE_HUFF)) {
-		if (!prepare_JPEGTables(tif))
-			return (0);
-		/* Mark the field present */
-		/* Can't use TIFFSetField since BEENWRITING is already set! */
-		TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
-		tif->tif_flags |= TIFF_DIRTYDIRECT;
+                if( sp->jpegtables == NULL
+                    || memcpy(sp->jpegtables,"\0\0\0\0\0\0\0\0\0",8) == 0 )
+                {
+                        if (!prepare_JPEGTables(tif))
+                                return (0);
+                        /* Mark the field present */
+                        /* Can't use TIFFSetField since BEENWRITING is already set! */
+                        tif->tif_flags |= TIFF_DIRTYDIRECT;
+                        TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
+                }
 	} else {
 		/* We do not support application-supplied JPEGTables, */
 		/* so mark the field not present */