diff --git a/lib/image_processing/mini_magick.rb b/lib/image_processing/mini_magick.rb
index 40ca414..bdef31c 100644
--- a/lib/image_processing/mini_magick.rb
+++ b/lib/image_processing/mini_magick.rb
@@ -110,6 +110,7 @@ module ImageProcessing
           yield cmd if block_given?
           cmd.resize "#{width}x#{height}^"
           cmd.gravity gravity
+          cmd.background "rgba(255,255,255,0.0)" # transparent
           cmd.extent "#{width}x#{height}"
         end
       end