diff --git a/test/rack/conform/headers.rb b/test/rack/conform/headers.rb
index 6716177..badc9a4 100644
--- a/test/rack/conform/headers.rb
+++ b/test/rack/conform/headers.rb
@@ -20,3 +20,11 @@ def body(headers)
 ensure
 	response&.finish
 end
+
+it 'rejects invalid non-string headers' do
+	response = client.get("/headers", {}, body({'foo-count' => 123}))
+	
+	expect(response.status).to be == 500
+ensure
+	response&.finish
+end