diff --git a/includes/mime_detect.inc b/includes/mime_detect.inc
index d6998008..13b66cc8 100644
--- a/includes/mime_detect.inc
+++ b/includes/mime_detect.inc
@@ -372,4 +372,14 @@ 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 974d526e..d6c89e99 100644
--- a/islandora.module
+++ b/islandora.module
@@ -1109,3 +1109,20 @@ function islandora_download_clip(AbstractObject $object) {
   }
   exit();
 }
+
+/**
+ * Implements hook_file_mimetype_mapping_alter().
+ *
+ * Grab custom islandora mime type list
+ * and add any missing ext/mimes to the drupal mapping
+ */
+function islandora_file_mimetype_mapping_alter(&$mapping) {
+  $mime_detect = new MimeDetect();
+  $types = $mime_detect->getMimeTypes();
+  $diff = array_diff_key($types, $mapping['extensions']);
+  foreach ($diff as $ext => $mime) {
+    $mapping['mimetypes'][] = $mime;
+    end($mapping['mimetypes']);
+    $mapping['extensions'][$ext] = key($mapping['mimetypes']);
+  }
+}