diff --git a/lib/i18n/backend/base.rb b/lib/i18n/backend/base.rb
index e7b95272..cc5c02f4 100644
--- a/lib/i18n/backend/base.rb
+++ b/lib/i18n/backend/base.rb
@@ -241,9 +241,9 @@ def load_rb(filename)
         def load_yml(filename)
           begin
             if YAML.respond_to?(:unsafe_load_file) # Psych 4.0 way
-              YAML.unsafe_load_file(filename)
+              YAML.unsafe_load_file(filename, freeze: true, symbolize_names: true)
             else
-              YAML.load_file(filename)
+              YAML.load_file(filename, freeze: true, symbolize_names: true)
             end
           rescue TypeError, ScriptError, StandardError => e
             raise InvalidLocaleData.new(filename, e.inspect)
diff --git a/test/backend/simple_test.rb b/test/backend/simple_test.rb
index 960e8cc9..a22e7ab8 100644
--- a/test/backend/simple_test.rb
+++ b/test/backend/simple_test.rb
@@ -72,7 +72,7 @@ def setup
 
   test "simple load_yml: loads data from a YAML file" do
     data = I18n.backend.send(:load_yml, "#{locales_dir}/en.yml")
-    assert_equal({ 'en' => { 'foo' => { 'bar' => 'baz' } } }, data)
+    assert_equal({ :en => { :foo => { :bar => 'baz' } } }, data)
   end
 
   test "simple load_json: loads data from a JSON file" do