diff --git a/contrib/ruby/lib/trilogy/encoding.rb b/contrib/ruby/lib/trilogy/encoding.rb
index 0fae9fe3..e9adae0c 100644
--- a/contrib/ruby/lib/trilogy/encoding.rb
+++ b/contrib/ruby/lib/trilogy/encoding.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Trilogy
   module Encoding
     RUBY_ENCODINGS = {
diff --git a/contrib/ruby/test/client_test.rb b/contrib/ruby/test/client_test.rb
index 6b968e98..728193ea 100644
--- a/contrib/ruby/test/client_test.rb
+++ b/contrib/ruby/test/client_test.rb
@@ -1131,4 +1131,14 @@ def test_error_classes_exclusively_match_subclasses
     assert_operator SystemCallError, :===, klass.new
     assert_operator Trilogy::ConnectionError, :===, klass.new
   end
+
+  if defined?(::Ractor)
+    def test_is_ractor_compatible
+      ractor = Ractor.new do
+        client = TrilogyTest.new(nil).new_tcp_client
+        client.query("SELECT 1")
+      end
+      assert_equal [[1]], ractor.take.to_a
+    end
+  end
 end
diff --git a/contrib/ruby/test/test_helper.rb b/contrib/ruby/test/test_helper.rb
index 9505d76b..5b0411cb 100644
--- a/contrib/ruby/test/test_helper.rb
+++ b/contrib/ruby/test/test_helper.rb
@@ -21,10 +21,10 @@
 end
 
 class TrilogyTest < Minitest::Test
-  DEFAULT_HOST = ENV["MYSQL_HOST"] || "127.0.0.1"
+  DEFAULT_HOST = (ENV["MYSQL_HOST"] || "127.0.0.1").freeze
   DEFAULT_PORT = (port = ENV["MYSQL_PORT"].to_i) && port != 0 ? port : 3306
-  DEFAULT_USER = ENV["MYSQL_USER"] || "root"
-  DEFAULT_PASS = ENV["MYSQL_PASS"]
+  DEFAULT_USER = (ENV["MYSQL_USER"] || "root").freeze
+  DEFAULT_PASS = ENV["MYSQL_PASS"].freeze
 
   def assert_equal_timestamp(time1, time2)
     assert_equal time1.to_i, time2.to_i