diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml
index ab83f671a..4a94b9355 100644
--- a/doc/manual/command-ref/conf-file.xml
+++ b/doc/manual/command-ref/conf-file.xml
@@ -406,6 +406,12 @@ builtins.fetchurl {
 
   </varlistentry>
 
+  <varlistentry xml:id="conf-max-free"><term><literal>max-free</literal></term>
+
+    <listitem><para>This option defines after how many free bytes to stop collecting
+    garbage once the <literal>min-free</literal> condition gets triggered.</para></listitem>
+
+  </varlistentry>
 
   <varlistentry xml:id="conf-max-jobs"><term><literal>max-jobs</literal></term>
 
@@ -440,6 +446,17 @@ builtins.fetchurl {
 
   </varlistentry>
 
+  <varlistentry xml:id="conf-min-free"><term><literal>min-free</literal></term>
+
+    <listitem>
+      <para>When the disk reaches <literal>min-free</literal> bytes of free disk space during a build, nix
+        will start to garbage-collection until <literal>max-free</literal> bytes are available on the disk.
+        A value of <literal>0</literal> (the default) means that this feature is disabled.</para>
+      </para>
+    </listitem>
+
+  </varlistentry>
+
 
   <varlistentry xml:id="conf-netrc-file"><term><literal>netrc-file</literal></term>