diff --git a/chapter05/glibc.xml b/chapter05/glibc.xml
index 39aabd12c..d6974bb21 100644
--- a/chapter05/glibc.xml
+++ b/chapter05/glibc.xml
@@ -157,6 +157,12 @@ cd       build</userinput></screen>
 
     <para>Install the package:</para>
 
+    <warning><para>If <envar>LFS</envar> is not proprly set, and despite the
+    recommendations, you are building as root, the next command will install
+    the newly built glibc to your host system, which most likely will render it
+    unusable. So double check that the environment is correctly set for user
+    <systemitem class="username">lfs</systemitem>.</para></warning>
+
 <screen><userinput remap="install">make DESTDIR=$LFS install</userinput></screen>
 
     <variablelist>