diff --git a/notebook/static/base/js/dialog.js b/notebook/static/base/js/dialog.js
index 249838dd0..f97523cae 100644
--- a/notebook/static/base/js/dialog.js
+++ b/notebook/static/base/js/dialog.js
@@ -60,6 +60,7 @@ define(['jquery',
                 })
                 .append($("<button>")
                     .attr("type", "button")
+                    .attr("aria-label", i18n.msg._("close"))
                     .addClass("close")
                     .attr("data-dismiss", "modal")
                     .attr("aria-hidden", "true")