diff --git a/lib/rackstash/encoders/message.rb b/lib/rackstash/encoders/message.rb
index ef9a127..98e71ea 100644
--- a/lib/rackstash/encoders/message.rb
+++ b/lib/rackstash/encoders/message.rb
@@ -45,8 +45,10 @@ module Rackstash
         normalize_message(event)
         message = event[FIELD_MESSAGE]
 
-        tags = @tagged_fields.map { |key| format_tag event[key] }.compact.join
-        message = message.gsub(/^/) { tags } unless tags.empty?
+        unless message.empty?
+          tags = @tagged_fields.map { |key| format_tag event[key] }.compact.join
+          message = message.gsub(/^/) { tags } unless tags.empty?
+        end
 
         message
       end
diff --git a/spec/rackstash/encoders/message_spec.rb b/spec/rackstash/encoders/message_spec.rb
index af8e494..04869da 100644
--- a/spec/rackstash/encoders/message_spec.rb
+++ b/spec/rackstash/encoders/message_spec.rb
@@ -43,6 +43,17 @@ describe Rackstash::Encoders::Message do
         event = { 'message' => ["line1\n", "line2\n"] }
         expect(encoder.encode(event)).to eql "line1\nline2\n"
       end
+
+      it 'does not prefix fields on an empty message' do
+        event = { 'message' => [], 'tags' => ['foo', 'bar'] }
+        expect(encoder.encode(event)).to eql ''
+      end
+
+      it 'prefixes fields with a single newline' do
+        event = { 'message' => ["\n"], 'tags' => ['foo', 'bar'] }
+        expect(encoder.encode(event)).to eql "[foo,bar] \n"
+      end
+
     end
   end
 end