image_optim.gemspec in image_optim-0.31.3 vs image_optim.gemspec in image_optim-0.31.4

@@ -1,10 +1,10 @@
 # encoding: UTF-8
 
 Gem::Specification.new do |s|
   s.name        = 'image_optim'
-  s.version     = '0.31.3'
+  s.version     = '0.31.4'
   s.summary     = %q{Command line tool and ruby interface to optimize (lossless compress, optionally lossy) jpeg, png, gif and svg images using external utilities (advpng, gifsicle, jhead, jpeg-recompress, jpegoptim, jpegrescan, jpegtran, optipng, oxipng, pngcrush, pngout, pngquant, svgo)}
   s.homepage    = "https://github.com/toy/#{s.name}"
   s.authors     = ['Ivan Kuchin']
   s.license     = 'MIT'
 
@@ -13,10 +13,10 @@
   s.metadata = {
     'bug_tracker_uri'   => "https://github.com/toy/#{s.name}/issues",
     'changelog_uri'     => "https://github.com/toy/#{s.name}/blob/master/CHANGELOG.markdown",
     'documentation_uri' => "https://www.rubydoc.info/gems/#{s.name}/#{s.version}",
     'source_code_uri'   => "https://github.com/toy/#{s.name}",
-  }
+  } if s.respond_to?(:metadata=)
 
   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths = %w[lib]