diff --git a/lib/barby/outputter/cairo_outputter.rb b/lib/barby/outputter/cairo_outputter.rb
index <HASH>..<HASH> 100644
--- a/lib/barby/outputter/cairo_outputter.rb
+++ b/lib/barby/outputter/cairo_outputter.rb
@@ -1,3 +1,4 @@
+require 'barby/outputter'
 require 'cairo'
 require 'stringio'
 
diff --git a/lib/barby/outputter/png_outputter.rb b/lib/barby/outputter/png_outputter.rb
index <HASH>..<HASH> 100644
--- a/lib/barby/outputter/png_outputter.rb
+++ b/lib/barby/outputter/png_outputter.rb
@@ -1,3 +1,4 @@
+require 'barby/outputter'
 require 'png'
 
 module Barby
Require Outputter parent class for Png- and CairoOutputter