diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index f7906781..7fa1a31f 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -101,7 +101,7 @@ module ActiveModel
       if associated_data.respond_to?(:to_ary)
         associated_data.map { |elem| association.build_serializer(elem).serializable_hash }
       else
-        association.build_serializer(associated_data).serializable_hash
+        [association.build_serializer(associated_data).serializable_hash]
       end
     end
 
diff --git a/lib/active_model/serializer/associations.rb b/lib/active_model/serializer/associations.rb
index 5b6365e2..e78bce9c 100644
--- a/lib/active_model/serializer/associations.rb
+++ b/lib/active_model/serializer/associations.rb
@@ -49,7 +49,7 @@ module ActiveModel
         end
 
         def embedded_key
-          name
+          name.pluralize
         end
       end
 
diff --git a/test/unit/active_model/serializer/has_one_test.rb b/test/unit/active_model/serializer/has_one_test.rb
index bbec3967..b104d652 100644
--- a/test/unit/active_model/serializer/has_one_test.rb
+++ b/test/unit/active_model/serializer/has_one_test.rb
@@ -32,28 +32,28 @@ module ActiveModel
       def test_associations_embedding_objects_serialization_using_serializable_hash
         @association.embed = :objects
         assert_equal({
-          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile' => { 'name' => 'N1', 'description' => 'D1' }
+          'name' => 'Name 1', 'email' => 'mail@server.com', 'profiles' => [{ 'name' => 'N1', 'description' => 'D1' }]
         }, @user_serializer.serializable_hash)
       end
 
       def test_associations_embedding_objects_serialization_using_as_json
         @association.embed = :objects
         assert_equal({
-          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile' => { 'name' => 'N1', 'description' => 'D1' }
+          'name' => 'Name 1', 'email' => 'mail@server.com', 'profiles' => [{ 'name' => 'N1', 'description' => 'D1' }]
         }, @user_serializer.as_json)
       end
 
       def test_associations_embedding_ids_including_objects_serialization_using_serializable_hash
         @association.include = true
         assert_equal({
-          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile_id' => @user.profile.object_id, 'profile' => { 'name' => 'N1', 'description' => 'D1' }
+          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile_id' => @user.profile.object_id, 'profiles' => [{ 'name' => 'N1', 'description' => 'D1' }]
         }, @user_serializer.serializable_hash)
       end
 
       def test_associations_embedding_ids_including_objects_serialization_using_as_json
         @association.include = true
         assert_equal({
-          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile_id' => @user.profile.object_id, 'profile' => { 'name' => 'N1', 'description' => 'D1' }
+          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile_id' => @user.profile.object_id, 'profiles' => [{ 'name' => 'N1', 'description' => 'D1' }]
         }, @user_serializer.as_json)
       end
 
@@ -69,7 +69,7 @@ module ActiveModel
         end
 
         assert_equal({
-          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile_id' => @user.profile.object_id, 'profile' => { 'name' => 'fake' }
+          'name' => 'Name 1', 'email' => 'mail@server.com', 'profile_id' => @user.profile.object_id, 'profiles' => [{ 'name' => 'fake' }]
         }, @user_serializer.as_json)
       ensure
         @association.serializer_class = @old_serializer