diff --git a/sharethis.module b/sharethis.module
index e9b97a5..5434e6b 100644
--- a/sharethis.module
+++ b/sharethis.module
@@ -187,7 +187,7 @@ function sharethis_theme($existing, $type, $theme, $path) {
  * @return array
  *   An array of options.
  */
-function sharethis_get_light_options($data_options) {
+function sharethis_get_light_options(array $data_options) {
   // Provide the publisher ID.
   $paramsStLight = array(
     'publisher' => $data_options['publisherID'],