diff --git a/exe/repubmark b/exe/repubmark
index 46c0dea..6d3b236 100755
--- a/exe/repubmark
+++ b/exe/repubmark
@@ -8,10 +8,10 @@ require 'bundler/setup'
 
 require 'repubmark'
 
-FORMATS = %w[word_count html gemtext].freeze
-
-format = String(ARGV[0]).freeze
-raise "Invalid format: #{format.inspect}" unless FORMATS.include? format
+format = String(ARGV[0]).to_sym
+unless Repubmark::FORMATS.include? format
+  raise "Invalid format: #{format.inspect}"
+end
 
 template = $stdin.read.freeze
 
@@ -37,9 +37,9 @@ context.instance_eval template, __FILE__, __LINE__
 
 output =
   case format
-  when 'word_count' then $article.word_count
-  when 'html'       then $article.to_html
-  when 'gemtext'    then $article.to_gemtext
+  when :word_count then $article.word_count
+  when :html       then $article.to_html
+  when :gemtext    then $article.to_gemtext
   end.to_s.strip
 
 puts output unless output.empty?
diff --git a/lib/repubmark.rb b/lib/repubmark.rb
index d87c8d2..e70ed22 100644
--- a/lib/repubmark.rb
+++ b/lib/repubmark.rb
@@ -54,3 +54,7 @@ require_relative 'repubmark/elems/section'
 require_relative 'repubmark/elems/special'
 require_relative 'repubmark/elems/text'
 require_relative 'repubmark/elems/link'
+
+module Repubmark
+  FORMATS = %i[gemtext html].freeze
+end
diff --git a/lib/repubmark/elems/custom_logue.rb b/lib/repubmark/elems/custom_logue.rb
index 25e6e7e..a3bd396 100644
--- a/lib/repubmark/elems/custom_logue.rb
+++ b/lib/repubmark/elems/custom_logue.rb
@@ -3,8 +3,6 @@
 module Repubmark
   module Elems
     class CustomLogue < Base
-      FORMATS = %i[html gemtext].freeze
-
       parents :Article
 
       def initialize(parent)