diff --git a/doc/backends.rst b/doc/backends.rst
index 69c39fb4..447db9bc 100644
--- a/doc/backends.rst
+++ b/doc/backends.rst
@@ -10,6 +10,8 @@ Memory
 Canaille comes with a lightweight inmemory backend by default.
 This backend is only for test purpose and should not be used in production environments.
 
+It is used when the ``BACKENDS`` configuration parameter is unset or empty.
+
 LDAP
 ====