diff --git a/grade/grading/form/guide/styles.css b/grade/grading/form/guide/styles.css
index 9060d817e3a..e3cd9dcb903 100644
--- a/grade/grading/form/guide/styles.css
+++ b/grade/grading/form/guide/styles.css
@@ -237,3 +237,7 @@
     margin: 0;
     width: auto;
 }
+.gradingform_guide_comment_chooser {
+    max-height: 80vh;
+    overflow-y: auto;
+}