diff --git a/includes/mime_detect.inc b/includes/mime_detect.inc
index 3c3741dd..13b66cc8 100644
--- a/includes/mime_detect.inc
+++ b/includes/mime_detect.inc
@@ -376,7 +376,7 @@ class MimeDetect {
    * Gets MIME type array.
    *
    * @return array
-   *   returns associative array with exts and mimetypes
+   *   Returns associative array with exts and mimetypes.
    */
   public function getMimeTypes() {
     return $this->protectedMimeTypes;
diff --git a/islandora.module b/islandora.module
index 3899ddb9..d6c89e99 100644
--- a/islandora.module
+++ b/islandora.module
@@ -1113,22 +1113,16 @@ function islandora_download_clip(AbstractObject $object) {
 /**
  * Implements hook_file_mimetype_mapping_alter().
  *
- * Grab custom islandora mime type list and add any missing ext/mimes to the drupal mapping
- *
- * @param array $mapping
- *   The Drupal mimetype mapping.
+ * Grab custom islandora mime type list
+ * and add any missing ext/mimes to the drupal mapping
  */
 function islandora_file_mimetype_mapping_alter(&$mapping) {
   $mime_detect = new MimeDetect();
   $types = $mime_detect->getMimeTypes();
   $diff = array_diff_key($types, $mapping['extensions']);
   foreach ($diff as $ext => $mime) {
-    if (!isset($mapping['extensions'][$ext])) {
-      $mapping['mimetypes'][] = $mime;
-      $last = end($mapping['mimetypes']);
-      reset($mapping['mimetypes']);
-      $key = array_search($mime, $mapping['mimetypes']);
-      $mapping['extensions'][$ext] = $key;
-    }
+    $mapping['mimetypes'][] = $mime;
+    end($mapping['mimetypes']);
+    $mapping['extensions'][$ext] = key($mapping['mimetypes']);
   }
 }