diff --git a/htdocs/core/lib/files.lib.php b/htdocs/core/lib/files.lib.php
index 8a1fecd999a..3e7e2796eca 100644
--- a/htdocs/core/lib/files.lib.php
+++ b/htdocs/core/lib/files.lib.php
@@ -1556,6 +1556,8 @@ function dol_add_file_process($upload_dir, $allowoverwrite=0, $donotupdatesessio
 				$destfull = $info['dirname'].'/'.dol_sanitizeFileName($info['filename'].'.'.strtolower($info['extension']));
 				$info = pathinfo($destfile);
 				$destfile = dol_sanitizeFileName($info['filename'].'.'.strtolower($info['extension']));
+				// We apply dol_string_nohtmltag also to clean file names (this remove duplicate spaces) because
+				// this function is also applied when we make try to download file (by the GETPOST(filename, 'alphanohtml') call).
 				$destfile = dol_string_nohtmltag($destfile);
 				$destfull = dol_string_nohtmltag($destfull);
 				$resupload = dol_move_uploaded_file($TFile['tmp_name'][$i], $destfull, $allowoverwrite, 0, $TFile['error'][$i], 0, $varfiles);