diff --git a/docs/topics/serialization.txt b/docs/topics/serialization.txt
index c8acc85..0f3432d 100644
--- a/docs/topics/serialization.txt
+++ b/docs/topics/serialization.txt
@@ -38,6 +38,11 @@ This is useful if you want to serialize data directly to a file-like object
     out = open("file.xml", "w")
     xml_serializer.serialize(SomeModel.objects.all(), stream=out)
 
+.. note::
+    
+    Calling :func:`~django.core.serializers.get_serializer` with an unknown
+    :ref:`format <serialization-formats>` will raise a ``KeyError``.
+
 Subset of fields
 ~~~~~~~~~~~~~~~~