diff --git a/mappers/filefield.inc b/mappers/filefield.inc
index 1e8c59f..67d19c3 100644
--- a/mappers/filefield.inc
+++ b/mappers/filefield.inc
@@ -52,7 +52,7 @@ function filefield_feeds_set_target($node, $field_name, $value) {
       $enclosures[] = $v;
     }
     elseif (valid_url($v)) {
-      $enclosures[$k] = new FeedsEnclosure($v, 'application/octet-stream');
+      $enclosures[$k] = new FeedsEnclosure($v, file_get_mimetype($v));
     }
   }