diff --git a/phpBB/includes/functions_download.php b/phpBB/includes/functions_download.php
index 9adbfc9baf..b295d4cd1e 100644
--- a/phpBB/includes/functions_download.php
+++ b/phpBB/includes/functions_download.php
@@ -413,7 +413,7 @@ function set_modified_headers($stamp, $browser)
 	global $request;
 
 	// let's see if we have to send the file at all
-	$last_load 	=  $request->header('Modified-Since') ? strtotime(trim($request->header('Modified-Since'))) : false;
+	$last_load 	=  $request->header('If-Modified-Since') ? strtotime(trim($request->header('If-Modified-Since'))) : false;
 
 	if (strpos(strtolower($browser), 'msie 6.0') === false && !phpbb_is_greater_ie_version($browser, 7))
 	{