diff --git a/chapter05/kernel-exp.xml b/chapter05/kernel-exp.xml
index bc304a424..2155c481b 100644
--- a/chapter05/kernel-exp.xml
+++ b/chapter05/kernel-exp.xml
@@ -1,6 +1,11 @@
 <sect2>
 <title>Command explanations</title>
 
+<para>
+<userinput>make mrproper:</userinput> This will ensure that the kernel
+tree is absolutely clean.
+</para>
+
 <para>
 <userinput>yes "" | make config:</userinput> This runs make config and
 answers with the default answer to every question the config script asks