1 files changed, 3 insertions, 1 deletions
diff --git a/classes/File.php b/classes/File.php
index 33273bbdc..c9477f5f1 100644
--- a/classes/File.php
+++ b/classes/File.php
@@ -286,7 +286,9 @@ class File extends Memcached_DataObject
 
         if(! isset($this->filename)){
             $notEnclosureMimeTypes = array(null,'text/html','application/xhtml+xml');
-            $mimetype = strtolower($this->mimetype);
+            if($mimetype != null){
+                $mimetype = strtolower($this->mimetype);
+            }
             $semicolon = strpos($mimetype,';');
             if($semicolon){
                 $mimetype = substr($mimetype,0,$semicolon);