diff --git a/includes/mime_detect.inc b/includes/mime_detect.inc
index 03ece01f..8aae5393 100644
--- a/includes/mime_detect.inc
+++ b/includes/mime_detect.inc
@@ -132,7 +132,8 @@ class MimeDetect {
     'wbxml' => 'application/vnd.wap.wbxml',
     'xht' => 'application/xhtml+xml',
     'xhtml' => 'application/xhtml+xml',
-    'xsl' => 'text/xml',
+    'xsl' => 'text/xsl',
+    'xslt' => 'text/xsl',
     'xml' => 'text/xml',
     'csv' => 'text/csv',
     'tsv' => 'text/tab-separated-values',