diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml
index 3851cf18d..6a23b8f1f 100644
--- a/doc/manual/command-ref/conf-file.xml
+++ b/doc/manual/command-ref/conf-file.xml
@@ -438,7 +438,9 @@ builtins.fetchurl {
     that Nix will try to build in parallel.  The default is
     <literal>1</literal>. The special value <literal>auto</literal>
     causes Nix to use the number of CPUs in your system.  <literal>0</literal>
-    is useful when using remote builders to prevent any local builds.  It can be
+    is useful when using remote builders to prevent any local builds (except for
+    <literal>preferLocalBuild</literal> derivation attribute which executes locally
+    regardless).  It can be
     overridden using the <option
     linkend='opt-max-jobs'>--max-jobs</option> (<option>-j</option>)
     command line switch.</para></listitem>