diff --git a/theme/boost/scss/moodle/undo.scss b/theme/boost/scss/moodle/undo.scss
index 982e6bff12b..aea2dc89c7a 100644
--- a/theme/boost/scss/moodle/undo.scss
+++ b/theme/boost/scss/moodle/undo.scss
@@ -138,3 +138,12 @@ ol {
     max-height: calc(100vh - #{$navbar-height});
     overflow-y: auto;
 }
+
+// Dont allow z-index creep anywhere.
+.page-item {
+  &.active .page-link {
+    @include plain-hover-focus {
+      z-index: inherit;
+    }
+  }
+}