diff --git a/includes/mime_detect.inc b/includes/mime_detect.inc
index 0914f62b..c92b5a15 100644
--- a/includes/mime_detect.inc
+++ b/includes/mime_detect.inc
@@ -366,4 +366,15 @@ class MimeDetect {
     return $out;
   }
 
+  /**
+   * Gets MIME type array.
+   *
+   * @return array
+   *   returns associative array with exts and mimetypes
+   */
+  public function getMimeTypes() {
+    return $this->protectedMimeTypes;
+  }
+
 }
+
diff --git a/islandora.module b/islandora.module
index ad9e569e..db5147b3 100644
--- a/islandora.module
+++ b/islandora.module
@@ -1097,3 +1097,26 @@ function islandora_download_clip(AbstractObject $object) {
   }
   exit();
 }
+
+/**
+ * Implements hook_file_mimetype_mapping_alter().
+ *
+ * Grab custom islandora mime type list and add any missing ext/mimes to the drupal mapping
+ *
+ * @param array $mapping
+ *   The Drupal mimetype mapping.
+ */
+function islandora_file_mimetype_mapping_alter(&$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;
+    }
+  }
+}
\ No newline at end of file