diff --git a/CHANGELOG.md b/CHANGELOG.md
index 027840f..9a00b68 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- fix array casts with `Ch` subtype https://github.com/plausible/ch/pull/118
+
 ## 0.2.0 (2023-07-28)
 
 - move loading and dumping from `Ch` type to the adapter https://github.com/plausible/ch/pull/112
diff --git a/lib/ch.ex b/lib/ch.ex
index 6313c79..a027102 100644
--- a/lib/ch.ex
+++ b/lib/ch.ex
@@ -127,7 +127,7 @@ defmodule Ch do
       end
     end
 
-    def cast(value, {:array, _type} = array), do: Ecto.Type.cast(array, value)
+    def cast(value, {:array, type}), do: Ecto.Type.cast({:array, type(type)}, value)
     def cast(value, {:nullable, type}), do: cast(value, type)
     def cast(value, {:low_cardinality, type}), do: cast(value, type)
     def cast(value, {:simple_aggregate_function, _name, type}), do: cast(value, type)
diff --git a/test/ch/ecto_type_test.exs b/test/ch/ecto_type_test.exs
index 91fde41..0c14533 100644
--- a/test/ch/ecto_type_test.exs
+++ b/test/ch/ecto_type_test.exs
@@ -330,6 +330,33 @@ defmodule Ch.EctoTypeTest do
     assert {:ok, "something"} = Ecto.Type.load(type, "something")
   end
 
+  test "SimpleAggregateFunction(groupArrayArray, Array(DateTime('UTC')))" do
+    assert {:parameterized, Ch,
+            {:simple_aggregate_function, "groupArrayArray", {:array, {:datetime, "UTC"}}}} =
+             type =
+             Ecto.ParameterizedType.init(Ch,
+               type: "SimpleAggregateFunction(groupArrayArray, Array(DateTime('UTC')))"
+             )
+
+    assert Ecto.Type.type(type) == type
+
+    assert Ecto.Type.format(type) ==
+             "#Ch<SimpleAggregateFunction(groupArrayArray, Array(DateTime('UTC')))>"
+
+    assert {:ok, [~U[2022-11-24 11:57:23Z]]} = Ecto.Type.cast(type, [~U[2022-11-24 11:57:23Z]])
+    assert {:ok, [~U[2022-11-24 11:57:23Z]]} = Ecto.Type.cast(type, ["2022-11-24 11:57:23Z"])
+    assert {:ok, []} = Ecto.Type.cast(type, [])
+    assert {:ok, nil} = Ecto.Type.cast(type, nil)
+
+    assert :error = Ecto.Type.cast(type, [~c"something"])
+    assert :error = Ecto.Type.cast(type, [:something])
+    assert :error = Ecto.Type.cast(type, [123])
+    assert :error = Ecto.Type.cast(type, 123)
+
+    assert {:ok, "no-op"} = Ecto.Type.dump(type, "no-op")
+    assert {:ok, "no-op"} = Ecto.Type.load(type, "no-op")
+  end
+
   # TODO check size?
   test "FixedString(3)" do
     assert {:parameterized, Ch, {:fixed_string, 3}} =