diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt
index d47f8d3a7f..0328295c9b 100644
--- a/docs/ref/models/querysets.txt
+++ b/docs/ref/models/querysets.txt
@@ -2631,6 +2631,12 @@ aggregate functions, see
     aggregation on date/time fields in SQLite will raise
     ``NotImplementedError``.
 
+.. admonition:: Note
+
+    Aggregation functions will return ``None`` when used with an empty
+    ``QuerySet``. For example, the ``Count`` aggregation function will return
+    ``None`` instead of ``0`` if the ``QuerySet`` contains no entries.
+
 Avg
 ~~~