diff --git a/theme/boost/scss/moodle/forms.scss b/theme/boost/scss/moodle/forms.scss
index 7194c865ecf..3d07b0b437b 100644
--- a/theme/boost/scss/moodle/forms.scss
+++ b/theme/boost/scss/moodle/forms.scss
@@ -296,7 +296,8 @@ fieldset.coursesearchbox label {
     font-size: large;
 }
 
-/* Non-bootstrap selects with a size show their contents outside of the element. Remove when we update to stable bootstrap 4. */
+/* Non-bootstrap selects with a size show their contents outside of the element.
+ * Remove when we update to stable bootstrap 4. (MDL-56511) */
 select[size],
 select[multiple] {
     overflow: auto;