additional check if headers can be modified

1 files changed, 1 insertions, 1 deletions

diff --git a/itjs.class b/itjs.class
index c4e91d5..d2aba92 100644
--- a/itjs.class
+++ b/itjs.class
@@ -195,7 +195,7 @@ static function checksum($fnlist)
 	{
 		$origheaders = headers_list();
 		$result = it_cache::put($key, substr(md5(itjs::filecontents(is_array($fnlist) ? $fnlist : itjs::filenames($fnlist), false)), 0, 8));
-		if (headers_list() != $origheaders)
+		if (!headers_sent() && headers_list() != $origheaders)
 		{
 			header_remove();
 			foreach ($origheaders as $origheader)