diff --git a/question/preview.php b/question/preview.php
index 5212b5e2ca4..50b22c6ed8e 100644
--- a/question/preview.php
+++ b/question/preview.php
@@ -275,6 +275,10 @@ print_collapsible_region_end();
 // Display the settings form.
 $optionsform->display();
 
+$PAGE->requires->js_module('core_question_engine');
+$PAGE->requires->strings_for_js(array(
+    'closepreview',
+), 'question');
 $PAGE->requires->yui_module('moodle-question-preview', 'M.question.preview.init');
 echo $OUTPUT->footer();
 
diff --git a/question/yui/build/moodle-question-preview/moodle-question-preview-debug.js b/question/yui/build/moodle-question-preview/moodle-question-preview-debug.js
index 79222869160..408dc554e11 100644
--- a/question/yui/build/moodle-question-preview/moodle-question-preview-debug.js
+++ b/question/yui/build/moodle-question-preview/moodle-question-preview-debug.js
@@ -24,18 +24,22 @@ YUI.add('moodle-question-preview', function (Y, NAME) {
  */
 
 M.question = M.question || {};
+M.question.preview = M.question.preview || {};
 
 /**
  * Initialise JavaScript-specific parts of the question preview popup.
  */
-M.question.preview.init = function(Y) {
+M.question.preview.init = function() {
     M.core_question_engine.init_form(Y, '#responseform');
 
     // Add a close button to the window.
-    var closebutton = Y.Node.create('<input type="button" />');
-    closebutton.set('value', M.str.question.closepreview);
+    var closebutton = Y.Node.create('<input type="button" />')
+            .set('value', M.util.get_string('closepreview', 'question'));
+
+    closebutton.on('click', function() {
+        window.close();
+    });
     Y.one('#previewcontrols').append(closebutton);
-    Y.on('click', function() { window.close(); }, closebutton);
 
     // Stop a question form being submitted more than once.
     Y.on('submit', M.core_question_engine.prevent_repeat_submission, '#mform1', null, Y);
diff --git a/question/yui/build/moodle-question-preview/moodle-question-preview-min.js b/question/yui/build/moodle-question-preview/moodle-question-preview-min.js
index 4f8598dde48..fea085d2a41 100644
--- a/question/yui/build/moodle-question-preview/moodle-question-preview-min.js
+++ b/question/yui/build/moodle-question-preview/moodle-question-preview-min.js
@@ -1 +1 @@
-YUI.add("moodle-question-preview",function(e,t){M.question=M.question||{},M.question.preview.init=function(e){M.core_question_engine.init_form(e,"#responseform");var t=e.Node.create('<input type="button" />');t.set("value",M.str.question.closepreview),e.one("#previewcontrols").append(t),e.on("click",function(){window.close()},t),e.on("submit",M.core_question_engine.prevent_repeat_submission,"#mform1",null,e)}},"@VERSION@",{requires:["base","dom","event-delegate","event-key","core_question_engine"]});
+YUI.add("moodle-question-preview",function(e,t){M.question=M.question||{},M.question.preview=M.question.preview||{},M.question.preview.init=function(){M.core_question_engine.init_form(e,"#responseform");var t=e.Node.create('<input type="button" />').set("value",M.util.get_string("closepreview","question"));t.on("click",function(){window.close()}),e.one("#previewcontrols").append(t),e.on("submit",M.core_question_engine.prevent_repeat_submission,"#mform1",null,e)}},"@VERSION@",{requires:["base","dom","event-delegate","event-key","core_question_engine"]});
diff --git a/question/yui/build/moodle-question-preview/moodle-question-preview.js b/question/yui/build/moodle-question-preview/moodle-question-preview.js
index 79222869160..408dc554e11 100644
--- a/question/yui/build/moodle-question-preview/moodle-question-preview.js
+++ b/question/yui/build/moodle-question-preview/moodle-question-preview.js
@@ -24,18 +24,22 @@ YUI.add('moodle-question-preview', function (Y, NAME) {
  */
 
 M.question = M.question || {};
+M.question.preview = M.question.preview || {};
 
 /**
  * Initialise JavaScript-specific parts of the question preview popup.
  */
-M.question.preview.init = function(Y) {
+M.question.preview.init = function() {
     M.core_question_engine.init_form(Y, '#responseform');
 
     // Add a close button to the window.
-    var closebutton = Y.Node.create('<input type="button" />');
-    closebutton.set('value', M.str.question.closepreview);
+    var closebutton = Y.Node.create('<input type="button" />')
+            .set('value', M.util.get_string('closepreview', 'question'));
+
+    closebutton.on('click', function() {
+        window.close();
+    });
     Y.one('#previewcontrols').append(closebutton);
-    Y.on('click', function() { window.close(); }, closebutton);
 
     // Stop a question form being submitted more than once.
     Y.on('submit', M.core_question_engine.prevent_repeat_submission, '#mform1', null, Y);
diff --git a/question/yui/src/preview/js/preview.js b/question/yui/src/preview/js/preview.js
index 744253a29c9..a366a4eba9f 100644
--- a/question/yui/src/preview/js/preview.js
+++ b/question/yui/src/preview/js/preview.js
@@ -22,18 +22,22 @@
  */
 
 M.question = M.question || {};
+M.question.preview = M.question.preview || {};
 
 /**
  * Initialise JavaScript-specific parts of the question preview popup.
  */
-M.question.preview.init = function(Y) {
+M.question.preview.init = function() {
     M.core_question_engine.init_form(Y, '#responseform');
 
     // Add a close button to the window.
-    var closebutton = Y.Node.create('<input type="button" />');
-    closebutton.set('value', M.str.question.closepreview);
+    var closebutton = Y.Node.create('<input type="button" />')
+            .set('value', M.util.get_string('closepreview', 'question'));
+
+    closebutton.on('click', function() {
+        window.close();
+    });
     Y.one('#previewcontrols').append(closebutton);
-    Y.on('click', function() { window.close(); }, closebutton);
 
     // Stop a question form being submitted more than once.
     Y.on('submit', M.core_question_engine.prevent_repeat_submission, '#mform1', null, Y);