diff --git a/ruby/spec/message_api_spec.rb b/ruby/spec/message_api_spec.rb
index 65718ba63..8b99264c3 100644
--- a/ruby/spec/message_api_spec.rb
+++ b/ruby/spec/message_api_spec.rb
@@ -12,13 +12,59 @@
   let(:api_instance_mock) { double("MessageApi") }
   let(:api_class_mock) { double("MessageApiClass") }
 
-  # Mock out the API calls
-  before(:each) do
-    stub_const("Svix::MessageApi", api_class_mock)
-    expect(api_class_mock).to receive(:new).with(param_mock).and_return(api_instance_mock)
+  describe "message_in_raw" do
+    it "works without content-type" do
+      payload = "{ \"x\": true }"
+      msg_in = Svix.message_in_raw(event_type: "x", payload: payload)
+
+      expect(msg_in.event_type).to eq("x")
+      expect(msg_in.payload).to eq({})
+      expect(msg_in.transformations_params[:rawPayload]).to eq(payload)
+      expect(msg_in.transformations_params[:headers]).to eq(nil)
+    end
+
+    it "works with content-type" do
+      payload = "Hello, World!"
+      content_type = "text/plain"
+      msg_in = Svix.message_in_raw(event_type: "x", payload: payload, content_type: content_type)
+
+      expect(msg_in.event_type).to eq("x")
+      expect(msg_in.payload).to eq({})
+      expect(msg_in.transformations_params[:rawPayload]).to eq(payload)
+      expect(msg_in.transformations_params[:headers][:'content-type']).to eq(content_type)
+    end
+
+    it "works with other transformations params" do
+      payload = "Hello, World!"
+      content_type = "text/plain"
+      msg_in = Svix.message_in_raw(
+        event_type: "x",
+        payload: payload,
+        content_type: content_type,
+        transformations_params: {
+          :foo => "bar",
+          :headers => {
+            :'x-custom' => "baz",
+          },
+        },
+      )
+
+      expect(msg_in.event_type).to eq("x")
+      expect(msg_in.payload).to eq({})
+      expect(msg_in.transformations_params[:foo]).to eq("bar")
+      expect(msg_in.transformations_params[:rawPayload]).to eq(payload)
+      expect(msg_in.transformations_params[:headers][:'content-type']).to eq(content_type)
+      expect(msg_in.transformations_params[:headers][:'x-custom']).to eq("baz")
+    end
   end
 
   describe "#get" do
+    # Mock out the API calls
+    before(:each) do
+      stub_const("Svix::MessageApi", api_class_mock)
+      expect(api_class_mock).to receive(:new).with(param_mock).and_return(api_instance_mock)
+    end
+
     it "passes it's parameters to the correct method" do
       # Assert that the correct method is called with the correct parameters
       expect(api_instance_mock).to receive(:v1_message_get).with(app_id, msg_id, options)