diff --git a/test/property/test_webhook_handler.rb b/test/property/test_webhook_handler.rb
index 93fcd2eaa160ec2928dc8494957d622ae216a654..83b39eac08b6a0b80ada91aefb3a7601d7597b30 100644
--- a/test/property/test_webhook_handler.rb
+++ b/test/property/test_webhook_handler.rb
@@ -438,4 +438,17 @@ class WebhookPropertyTest < Minitest::Test
 		}
 	end
 	em :test_request_with_non_post_method_produces_no_output
+
+	def test_payload_without_message_or_type_returns_400
+		property_of {
+			metadata, example = Webhook.new(REDIS).generate
+			[choose("message", "type"), metadata, example]
+		}.check { |key, metadata, example|
+			example.delete(key)
+			result = invoke_webhook(example)
+			assert_equal [400, {}, "Missing params\n"], result
+			assert_empty written
+		}
+	end
+	em :test_payload_without_message_or_type_returns_400
 end