diff --git a/htdocs/admin/tools/export_files.php b/htdocs/admin/tools/export_files.php
index 384b08e19cf..4bae5f4862d 100644
--- a/htdocs/admin/tools/export_files.php
+++ b/htdocs/admin/tools/export_files.php
@@ -126,8 +126,10 @@ $utils = new Utils($db);
 
 if ($compression == 'zip') {
 	$file .= '.zip';
-	$excludefiles = '/(\.back|\.old|\.log|[\/\\\]temp[\/\\\]|documents[\/\\\]admin[\/\\\]documents[\/\\\])/i';
+
+	$excludefiles = '/(\.back|\.old|\.log|\.pdf_preview-.*\.png|[\/\\\]temp[\/\\\]|[\/\\\]admin[\/\\\]documents[\/\\\])/i';
 	$ret = dol_compress_dir(DOL_DATA_ROOT, $outputdir."/".$file, $compression, $excludefiles);
+
 	if ($ret < 0) {
 		if ($ret == -2) {
 			$langs->load("errors");