diff --git a/lib/topic_creator.rb b/lib/topic_creator.rb
index 5f4aa7f16e9..654fc716f4b 100644
--- a/lib/topic_creator.rb
+++ b/lib/topic_creator.rb
@@ -35,8 +35,9 @@ class TopicCreator
   def create
     topic = Topic.new(setup_topic_params)
     setup_tags(topic)
+
     if fields = @opts[:custom_fields]
-      topic.custom_fields = fields
+      topic.custom_fields.merge!(fields)
     end
 
     DiscourseEvent.trigger(:before_create_topic, topic, self)
diff --git a/spec/components/topic_creator_spec.rb b/spec/components/topic_creator_spec.rb
index c475a08e92f..36a8717b9ad 100644
--- a/spec/components/topic_creator_spec.rb
+++ b/spec/components/topic_creator_spec.rb
@@ -36,6 +36,18 @@ describe TopicCreator do
         expect(TopicCreator.create(moderator, Guardian.new(moderator), valid_attrs)).to be_valid
       end
 
+      it "supports both meta_data and custom_fields" do
+        opts = valid_attrs.merge(
+          meta_data: { import_topic_id: "foo" },
+          custom_fields: { import_id: "bar" }
+        )
+
+        topic = TopicCreator.create(admin, Guardian.new(admin), opts)
+
+        expect(topic.custom_fields["import_topic_id"]).to eq("foo")
+        expect(topic.custom_fields["import_id"]).to eq("bar")
+      end
+
       context 'regular user' do
         before { SiteSetting.min_trust_to_create_topic = TrustLevel[0] }