diff --git a/themes/bootstrap3/js/facets.js b/themes/bootstrap3/js/facets.js
index 0d83d63653e2d129e09080319ba43d090814c6b7..3a878564f652e255f895ce576fa2c5038a7205de 100644
--- a/themes/bootstrap3/js/facets.js
+++ b/themes/bootstrap3/js/facets.js
@@ -131,7 +131,7 @@ VuFind.register('lightbox_facets', function LightboxFacets() {
     lightboxFacetSorting();
     $('.js-facet-next-page').click(function facetLightboxMore() {
       var button = $(this);
-      var page = parseInt(this.dataset.page);
+      var page = parseInt(this.dataset.page, 10);
       if (button.attr('disabled')) {
         return false;
       }