diff --git a/rswag-specs/lib/rswag/specs/swagger_formatter.rb b/rswag-specs/lib/rswag/specs/swagger_formatter.rb
index b8061dc..d16aeb2 100644
--- a/rswag-specs/lib/rswag/specs/swagger_formatter.rb
+++ b/rswag-specs/lib/rswag/specs/swagger_formatter.rb
@@ -48,6 +48,8 @@ module Rswag
 
       def pretty_generate(doc)
         if @config.swagger_format == :yaml
+          # NOTE: Yaml will quite happily embed ruby-only classes such as symbols.
+          # clean_doc = stringify(doc)
           YAML.dump(doc)
         else # config errors are thrown in 'def swagger_format', no throw needed here
           JSON.pretty_generate(doc)
diff --git a/rswag-specs/spec/rswag/specs/swagger_formatter_spec.rb b/rswag-specs/spec/rswag/specs/swagger_formatter_spec.rb
index 2a29cde..6561f8a 100644
--- a/rswag-specs/spec/rswag/specs/swagger_formatter_spec.rb
+++ b/rswag-specs/spec/rswag/specs/swagger_formatter_spec.rb
@@ -74,6 +74,8 @@ module Rswag
           it 'writes the swagger_doc(s) as yaml' do
             expect(File).to exist("#{swagger_root}/v1/swagger.json")
             expect { JSON.parse(File.read("#{swagger_root}/v1/swagger.json")) }.to raise_error(JSON::ParserError)
+            # Psych::DisallowedClass would be raised if we do not pre-process ruby symbols
+            expect { YAML.safe_load(File.read("#{swagger_root}/v1/swagger.json")) }.not_to raise_error
           end
         end