diff --git a/docs/reference/gio/overview.xml b/docs/reference/gio/overview.xml
index 109392d65..6da4492d2 100644
--- a/docs/reference/gio/overview.xml
+++ b/docs/reference/gio/overview.xml
@@ -332,6 +332,19 @@ Gvfs is also heavily distributed and relies on a session bus to be present.
       </para>
     </formalpara>
 
+    <formalpara>
+      <title><envar>GIO_USE_FILE_MONITOR</envar></title>
+
+      <para>
+        This variable can be set to the name of a #GFileMonitor
+        implementation to override the default for debugging purposes.
+        The #GFileMonitor implementation for local files that is included
+        in GIO on Linux has the name "inotify", others that are built
+        are built as modules (depending on the platform) are called
+        "fam" and "fen".
+      </para>
+    </formalpara>
+
     <formalpara>
       <title><envar>GIO_USE_VOLUME_MONITOR</envar></title>