diff --git a/nixos/modules/security/grsecurity.xml b/nixos/modules/security/grsecurity.xml
index a991758021a1..97628b0fe329 100644
--- a/nixos/modules/security/grsecurity.xml
+++ b/nixos/modules/security/grsecurity.xml
@@ -347,7 +347,7 @@
 
       <listitem><para>
         <literal>pax_sanitize_slab={off|fast|full}</literal>: control kernel
-        slab object sanitization
+        slab object sanitization. Defaults to <literal>fast</literal>
       </para></listitem>
 
       <listitem><para>