diff --git a/.changelog/25372.txt b/.changelog/25372.txt
new file mode 100644
index 000000000000..78fc94618d20
--- /dev/null
+++ b/.changelog/25372.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+resource/aws_appstream_stack: Fix crash when setting `embed_host_domains`
+```
diff --git a/internal/service/appstream/stack.go b/internal/service/appstream/stack.go
index f26402c03ae7..a58b660c2b8d 100644
--- a/internal/service/appstream/stack.go
+++ b/internal/service/appstream/stack.go
@@ -211,7 +211,7 @@ func resourceStackCreate(ctx context.Context, d *schema.ResourceData, meta inter
 	}
 
 	if v, ok := d.GetOk("embed_host_domains"); ok {
-		input.EmbedHostDomains = flex.ExpandStringList(v.([]interface{}))
+		input.EmbedHostDomains = flex.ExpandStringSet(v.(*schema.Set))
 	}
 
 	if v, ok := d.GetOk("feedback_url"); ok {
diff --git a/internal/service/appstream/stack_test.go b/internal/service/appstream/stack_test.go
index eebcfaef2507..94cdf68cf798 100644
--- a/internal/service/appstream/stack_test.go
+++ b/internal/service/appstream/stack_test.go
@@ -95,6 +95,9 @@ func TestAccAppStreamStack_complete(t *testing.T) {
 					resource.TestCheckResourceAttr(resourceName, "name", rName),
 					acctest.CheckResourceAttrRFC3339(resourceName, "created_time"),
 					resource.TestCheckResourceAttr(resourceName, "description", descriptionUpdated),
+					resource.TestCheckResourceAttr(resourceName, "embed_host_domains.#", "2"),
+					resource.TestCheckTypeSetElemAttr(resourceName, "embed_host_domains.*", "example.com"),
+					resource.TestCheckTypeSetElemAttr(resourceName, "embed_host_domains.*", "subdomain.example.com"),
 				),
 			},
 			{
@@ -215,6 +218,8 @@ resource "aws_appstream_stack" "test" {
   name        = %[1]q
   description = %[2]q
 
+  embed_host_domains = ["example.com", "subdomain.example.com"]
+
   storage_connectors {
     connector_type = "HOMEFOLDERS"
   }