diff --git a/lib/ash_slug/changes/slugify.ex b/lib/ash_slug/changes/slugify.ex
index 44a138d..852853c 100644
--- a/lib/ash_slug/changes/slugify.ex
+++ b/lib/ash_slug/changes/slugify.ex
@@ -50,7 +50,7 @@ defmodule AshSlug.Changes.Slugify do
     Ash.Changeset.before_action(changeset, fn changeset ->
       with {attribute, opts} <- Keyword.pop(opts, :attribute),
            {into, opts} <- Keyword.pop(opts, :into, attribute),
-           {:ok, value} when is_binary(value) <- Ash.Changeset.fetch_argument_or_change(changeset, attribute),
+           {:ok, value} when is_binary(value) <- get_attribute(changeset, attribute),
            slug <- Slug.slugify(value, opts) do
         changeset
         |> Ash.Changeset.force_change_attribute(into, slug)
@@ -61,6 +61,13 @@ defmodule AshSlug.Changes.Slugify do
     end)
   end
 
+  defp get_attribute(changeset, attribute) do
+    case Ash.Changeset.fetch_argument_or_change(changeset, attribute) do
+      {:ok, %Ash.CiString{} = value} -> {:ok, Ash.CiString.value(value)}
+      res -> res
+    end
+  end
+
   @spec replace_lowercase_opts(Keyword.t()) :: Keyword.t()
   defp replace_lowercase_opts(opts) do
     Keyword.pop(opts, :lowercase?)
diff --git a/test/ash_slug_test.exs b/test/ash_slug_test.exs
index 566098d..a1472d1 100644
--- a/test/ash_slug_test.exs
+++ b/test/ash_slug_test.exs
@@ -12,6 +12,16 @@ defmodule AshSlugTest do
     assert resource.text1 == "Hello-World"
   end
 
+  test "ensure Ash.CiString value is slugified" do
+    resource =
+      AshSlugTest.Resource
+      |> Ash.Changeset.for_create(:create, %{text3: Ash.CiString.new("Hello, World!")})
+      |> Ash.Changeset.set_context(%{foo: :bar})
+      |> Ash.create!()
+
+    assert resource.text3_slug == "hello-world"
+  end
+
   test "ensure value is slugified into another attribute" do
     resource =
       AshSlugTest.Resource
diff --git a/test/support/resource.ex b/test/support/resource.ex
index 733c985..fb958aa 100644
--- a/test/support/resource.ex
+++ b/test/support/resource.ex
@@ -15,15 +15,18 @@ defmodule AshSlugTest.Resource do
     attribute(:text1, :string, public?: true)
     attribute(:text2, :string, public?: true)
     attribute(:text2_slug, :string)
+    attribute(:text3, :ci_string, public?: true)
+    attribute(:text3_slug, :string)
     attribute(:bool, :boolean, public?: true)
   end
 
   actions do
     create :create do
-      accept([:text1, :text2, :bool])
+      accept([:text1, :text2, :text3, :bool])
 
       change(slugify(:text1, lowercase?: false))
       change(slugify(:text2, into: :text2_slug))
+      change(slugify(:text3, into: :text3_slug))
       change(slugify(:bool))
     end
   end