diff --git a/lib/rackstash/formatter.rb b/lib/rackstash/formatter.rb
index 16a06ec..2d58197 100644
--- a/lib/rackstash/formatter.rb
+++ b/lib/rackstash/formatter.rb
@@ -25,4 +25,10 @@ module Rackstash
       "#{msg2str(msg)}\n"
     end
   end
+
+  class RawFormatter
+    def call(_severity, _timestamp, _progname, msg)
+      msg
+    end
+  end
 end
diff --git a/lib/rackstash/message.rb b/lib/rackstash/message.rb
index a26d877..29ce90f 100644
--- a/lib/rackstash/message.rb
+++ b/lib/rackstash/message.rb
@@ -6,7 +6,7 @@
 module Rackstash
   # This class and all its data are immutable after initialization
   class Message
-    RAW_FORMATTER = ->(_severity, _timestamp, _progname, msg) { msg }
+    RAW_FORMATTER = RawFormatter.new
 
     SEVERITY_LABEL = [
       'DEBUG'.freeze,
diff --git a/spec/rackstash/formatter_spec.rb b/spec/rackstash/formatter_spec.rb
index 09e7fd6..e9085f5 100644
--- a/spec/rackstash/formatter_spec.rb
+++ b/spec/rackstash/formatter_spec.rb
@@ -46,3 +46,12 @@ describe Rackstash::Formatter do
     expect(formatter.call('ERROR', Time.now, 'progname', object)).to eql "#{inspected}\n"
   end
 end
+
+describe Rackstash::RawFormatter do
+  let(:formatter) { Rackstash::RawFormatter.new }
+
+  it 'returns the message' do
+    msg = 'my message'
+    expect(formatter.call('ERROR', Time.now, 'progname', msg)).to equal msg
+  end
+end