diff --git a/doc/filters/batch.rst b/doc/filters/batch.rst
index cc50ec8e857..a1271735e49 100644
--- a/doc/filters/batch.rst
+++ b/doc/filters/batch.rst
@@ -49,3 +49,4 @@ Arguments
 
 * ``size``: The size of the batch; fractional numbers will be rounded up
 * ``fill``: Used to fill in missing items
+* ``preserve_keys``: Whether to preserve keys or not