diff --git a/mkdocs/docs/config/options.md b/mkdocs/docs/config/options.md
index 54cb9f32..4844640a 100644
--- a/mkdocs/docs/config/options.md
+++ b/mkdocs/docs/config/options.md
@@ -218,6 +218,7 @@ config file.
   needed. Really only needed for [exporting mergerfs via
   NFS](../remote_filesystems.md) (default: 0)
 * **noforget**: Effectively sets `remember-nodes` to infinity.
+* **allow-idmap=BOOL**: Enables idmap (identity mapping). (default: true)
 
 **NOTE:** Options are evaluated in the order listed so if the options
 are **func.rmdir=rand,category.action=ff** the **action** category