diff --git a/docs/releases/4.0.3.rst b/docs/releases/4.0.3.rst
new file mode 100644
index 000000000..a1119eeac
--- /dev/null
+++ b/docs/releases/4.0.3.rst
@@ -0,0 +1,26 @@
+============================
+Release notes for IRRd 4.0.3
+============================
+
+IRRd 4.0.3 was released on June 29th, 2019, and contains
+one change relating to referential integrity validation
+between RPSL objects.
+
+In earlier versions of IRRd, the `members` attribute of
+an `as-set`, along with several others,
+`were strongly validated`_. This meant it was not possible
+to add or update an `as-set`, if some of the members were
+not valid objects in the same source. The same applied
+to fields like `member-of` in a `route-set`.
+
+In IRRd 4.0.3, all references from `members`, `mp-member`,
+`mbrs-by-ref` and `member-of` are weak references. Their
+syntax is validated to be, e.g. for `as-set` members, a
+valid `as-set` name or a valid AS number. However, there
+is no validation on whether the objects actually exist.
+It is also possible to delete e.g. a `route-set`, even when
+the object is still set in `member-of` in a `route` object,
+or to reference a maintainer that does not exist in a
+`mbrs-by-ref`.
+
+.. _were strongly validated: https://github.com/irrdnet/irrd4/pull/240
diff --git a/docs/releases/index.rst b/docs/releases/index.rst
index 52f3d6d92..82a908a55 100644
--- a/docs/releases/index.rst
+++ b/docs/releases/index.rst
@@ -6,3 +6,4 @@ Release notes
 
    4.0.1
    4.0.2
+   4.0.3