diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 48f8965f7f..5b0e593c3d 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -4748,6 +4748,7 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
                     class.
                     Set the variable to "1" to prevent the ISO image from
                     being built.
+                    To enable building an ISO image, set the variable to "0".
                 </para>
             </glossdef>
         </glossentry>