diff --git a/wagtail/wagtailadmin/static_src/wagtailadmin/js/core.js b/wagtail/wagtailadmin/static_src/wagtailadmin/js/core.js
index 9c87d2244..f60b6fdb4 100644
--- a/wagtail/wagtailadmin/static_src/wagtailadmin/js/core.js
+++ b/wagtail/wagtailadmin/static_src/wagtailadmin/js/core.js
@@ -53,7 +53,7 @@ function initTagField(id, autocompleteUrl) {
  *      prompting the user even when nothing has been changed.
 */
 
-var canDirtyFormCheck = true;
+var dirtyFormCheckIsActive = true;
 
 function enableDirtyFormCheck(formSelector, options) {
     var $form = $(formSelector);
@@ -75,17 +75,17 @@ function enableDirtyFormCheck(formSelector, options) {
             }
         });
 
-        if (!canDirtyFormCheck) {
-            triggeredByIgnoredButton = true;
-        }
-
-        if (canDirtyFormCheck && !triggeredByIgnoredButton && (alwaysDirty || $form.serialize() != initialData)) {
+        if (dirtyFormCheckIsActive && !triggeredByIgnoredButton && (alwaysDirty || $form.serialize() != initialData)) {
             event.returnValue = confirmationMessage;
             return confirmationMessage;
         }
     });
 }
 
+function disableDirtyFormCheck() {
+    dirtyFormCheckIsActive = false;
+}
+
 $(function() {
     // Add class to the body from which transitions may be hung so they don't appear to transition as the page loads
     $('body').addClass('ready');
diff --git a/wagtail/wagtailadmin/static_src/wagtailadmin/js/page-editor.js b/wagtail/wagtailadmin/static_src/wagtailadmin/js/page-editor.js
index 79508d364..48b46177d 100644
--- a/wagtail/wagtailadmin/static_src/wagtailadmin/js/page-editor.js
+++ b/wagtail/wagtailadmin/static_src/wagtailadmin/js/page-editor.js
@@ -366,13 +366,13 @@ function initCollapsibleBlocks() {
 
 function initKeyboardShortcuts() {
     Mousetrap.bind(['mod+p'], function(e) {
-        canDirtyFormCheck = false;
+        disableDirtyFormCheck();
         $('.action-preview').trigger('click');
         return false;
     });
 
     Mousetrap.bind(['mod+s'], function(e) {
-        canDirtyFormCheck = false;
+        disableDirtyFormCheck();
         $('.action-save').trigger('click');
         return false;
     });