diff --git a/documentation/ref-manual/ref-classes.xml b/documentation/ref-manual/ref-classes.xml
index 7b8cd26848..f2c4c79c5a 100644
--- a/documentation/ref-manual/ref-classes.xml
+++ b/documentation/ref-manual/ref-classes.xml
@@ -1177,7 +1177,7 @@
         <link linkend='var-ICECC_DISABLED'><filename>ICECC_DISABLED</filename></link>
         variable to "1" as follows:
         <literallayout class='monospaced'>
-     INHERIT_DISTRO += "icecc"
+     INHERIT_DISTRO_append = " icecc"
      ICECC_DISABLED ??= "1"
         </literallayout>
         This practice makes sure everyone is using the same signatures but also