diff --git a/loopy/kernel/__init__.py b/loopy/kernel/__init__.py
index 22a45fac996f6eaf1737fb28ab51ab9ac4f9ead7..d7009900b5683d43effb594cf5b38498db8e09c1 100644
--- a/loopy/kernel/__init__.py
+++ b/loopy/kernel/__init__.py
@@ -109,6 +109,9 @@ class LoopKernel(RecordWithoutPickling):
     .. attribute:: preambles
     .. attribute:: preamble_generators
     .. attribute:: assumptions
+
+        A :class:`islpy.BasicSet` parameter domain.
+
     .. attribute:: local_sizes
     .. attribute:: temporary_variables