diff --git a/lib/jekyll-responsive-image/extra_image_generator.rb b/lib/jekyll-responsive-image/extra_image_generator.rb
index 5ea6c43..2ffd34b 100644
--- a/lib/jekyll-responsive-image/extra_image_generator.rb
+++ b/lib/jekyll-responsive-image/extra_image_generator.rb
@@ -2,6 +2,7 @@ module Jekyll
   module ResponsiveImage
     class ExtraImageGenerator < Jekyll::Generator
       include Jekyll::ResponsiveImage::Utils
+      include FileTest
 
       def generate(site)
         config = Config.new(site).to_h
@@ -9,11 +10,13 @@ module Jekyll
 
         config['extra_images'].each do |pathspec|
           Dir.glob(site.in_source_dir(pathspec)) do |image_path|
-            path = Pathname.new(image_path)
-            relative_image_path = path.relative_path_from(site_source)
+            if FileTest.file?(image_path)
+              path = Pathname.new(image_path)
+              relative_image_path = path.relative_path_from(site_source)
 
-            result = ImageProcessor.process(relative_image_path, config)
-            result[:resized].each { |image| keep_resized_image!(site, image) }
+              result = ImageProcessor.process(relative_image_path, config)
+              result[:resized].each { |image| keep_resized_image!(site, image) }
+            end
           end
         end
       end