diff --git a/bin/git-format-staged b/bin/git-format-staged
index faa78af..f325ac3 100755
--- a/bin/git-format-staged
+++ b/bin/git-format-staged
@@ -57,7 +57,7 @@ parser = OptionParser.new do |opt|
     puts FormatStaged::VERSION
     exit
   end
-  
+
   opt.on('--[no-]color', 'Colorizes output') do |value|
     parameters[:color_output] = value
   end
diff --git a/format-staged.gemspec b/format-staged.gemspec
index ac7abdc..6711751 100644
--- a/format-staged.gemspec
+++ b/format-staged.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.homepage    = 'https://github.com/5sw/format-staged'
   s.license     = 'MIT'
   s.required_ruby_version = '~> 2.7'
-  
+
   s.add_dependency 'colorize'
 
   s.add_development_dependency 'rake', '~> 13.0'
diff --git a/lib/format-staged/io.rb b/lib/format-staged/io.rb
index df472e3..c7cdaf5 100644
--- a/lib/format-staged/io.rb
+++ b/lib/format-staged/io.rb
@@ -31,15 +31,15 @@ class FormatStaged
     [pid, r]
   end
 
-  def read_output(r, lines: true, silent: false)
-    result = r.read
+  def read_output(output, lines: true, silent: false)
+    result = output.read
     splits = result.split("\n")
     if @verbose && !silent
       splits.each do |line|
         puts "< #{line}"
       end
     end
-    r.close
+    output.close
 
     lines ? splits : result
   end