diff --git a/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-detail.tt b/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-detail.tt
index 5c8bea0bf4..a7e9b9a5ef 100644
--- a/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-detail.tt
+++ b/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-detail.tt
@@ -1827,7 +1827,7 @@
                         .each(function () {
                             if (!this.complete || this.naturalHeight == 0) check_complete = 0;
                         });
-                    if (check_complete) $(coverSlide).css('background-image', 'none');
+                    if (check_complete) $(coverSlide).css("background-image", "none");
                 }
             });