diff --git a/rubberin b/rubberin
index 6f7a64f..03e6365 100755
--- a/rubberin
+++ b/rubberin
@@ -25,17 +25,18 @@
 # Public License for more details.
 #
 # You should have received a copy of the GNU General Public License along
-# with this p rogram; if not, write to the Free Software Foundation, Inc.,
+# with this program; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
-require 'getoptlong'
-require 'rb-inotify'
-require 'pathname'
+require "getoptlong"
+require "rb-inotify"
+require "pathname"
 
 # Small necessary Pathname class extension.
 class Pathname
   def extname=(ext)
-    raise "Invalid extension" unless ext.is_a? String and ext.match(/^\./)
+    raise "Invalid extension" unless ext.is_a?(String) && ext.match(/^\./)
+
     @path.sub!(/#{extname}$/, ext)
   end
 end
@@ -44,7 +45,7 @@ end
 
 # Print the usage.
 def usage
-  puts "Usage: #{Program} [options]... [tex-file] [rubber-options]..."
+  puts "Usage: #{PROGRAM} [options]... [tex-file] [rubber-options]..."
 end
 
 # Print the command line help.
@@ -62,34 +63,35 @@ end
 
 # Compile the input file using the right options based on the mode.
 def compile(infile, mode)
-  mode_opt = {:pdf   => "--pdf",
-              :ps    => "--ps",
-              :pspdf => "--ps --pdf"}[mode]
-  params = ARGV.join(' ')
-  err_file = infile.with_extname('err')
+  mode_opt = { pdf: "--pdf",
+               ps: "--ps",
+               pspdf: "--ps --pdf" }[mode]
+  params = ARGV.join(" ")
+  err_file = infile.with_extname("err")
 
   _ret = system "rubber --inplace #{mode_opt} #{params} #{infile} 2> #{err_file}"
   File.open(err_file) { |file| puts file.read }
   # Remove the output save file if compile was succesful.
-  #clean(infile) if ret
+  # clean(infile) if ret
 end
 
 # Start the right viewer based on the mode.
 def view(infile, mode)
   case mode
-    when :dvi
-      exec "xdvi.bin", "-watchfile", "1",
-                       "-name", "xdvi",  infile.with_extname('dvi').to_s
-    when :ps
-      exec "evince", infile.with_extname('ps').to_s
-    when :pdf, :pspdf
-      exec "evince", infile.with_extname('pdf').to_s
+  when :dvi
+    exec "xdvi.bin",
+         "-watchfile", "1",
+         "-name", "xdvi", infile.with_extname("dvi").to_s
+  when :ps
+    exec "evince", infile.with_extname("ps").to_s
+  when :pdf, :pspdf
+    exec "evince", infile.with_extname("pdf").to_s
   end
 end
 
 # Clean up cruft related to compilation of the input file.
 def clean(infile)
-  err_file = infile.with_extname('err')
+  err_file = infile.with_extname("err")
   File.unlink(err_file) if err_file.exist?
   system "rubber --clean --inplace #{infile}"
 end
@@ -97,55 +99,55 @@ end
 # Reload the right viewer based on the mode.
 def reload(infile, mode)
   case mode
-    when :ps
-      system "evince", infile.with_extname('ps').to_s
-    when :pdf, :pspdf
-      system "evince", infile.with_extname('pdf').to_s
+  when :ps
+    system "evince", infile.with_extname("ps").to_s
+  when :pdf, :pspdf
+    system "evince", infile.with_extname("pdf").to_s
   end
 end
 
 ## Initialisation
-Program = File.basename $0
-Version = '0.6'
+PROGRAM = File.basename($PROGRAM_NAME).freeze
+VERSION = "0.6".freeze
 
 # Parse the command line options.
 # Determine the compile mode from the options.
 mode = :dvi
-opts = GetoptLong.new(
-                      [ "--help",    "-h", GetoptLong::NO_ARGUMENT ],
-                      [ "--ps",      "-p", GetoptLong::NO_ARGUMENT ],
-                      [ "--pdf",     "-d", GetoptLong::NO_ARGUMENT ],
-                      [ "--version", "-v", GetoptLong::NO_ARGUMENT ])
+opts = GetoptLong.new(["--help",    "-h", GetoptLong::NO_ARGUMENT],
+                      ["--ps",      "-p", GetoptLong::NO_ARGUMENT],
+                      ["--pdf",     "-d", GetoptLong::NO_ARGUMENT],
+                      ["--version", "-v", GetoptLong::NO_ARGUMENT])
 opts.ordering = GetoptLong::REQUIRE_ORDER
 opts.quiet = true
-opts.each do |opt, arg|
+opts.each do |opt, _arg|
   case opt
-    when "--help"
-      help
-      exit 0
-    when "--ps"
-      mode = :ps
-    when "--pdf"
-      mode = if mode == :ps then :pspdf
-             else :pdf
-             end
-    when "--version"
-      puts "#{Program} #{Version}"
-      exit 0
+  when "--help"
+    help
+    exit 0
+  when "--ps"
+    mode = :ps
+  when "--pdf"
+    mode = if mode == :ps then :pspdf
+           else :pdf
+           end
+  when "--version"
+    puts "#{PROGRAM} #{VERSION}"
+    exit 0
   end
 end
 
 # Get the input file from the arguments.
-if ARGV.length < 1
+if ARGV.empty?
   usage
   exit 1
 else
   infile = Pathname.new(ARGV.shift)
   def infile.base
-    self.basename(self.extname)
+    basename(extname)
   end
+
   def infile.with_extname(ext)
-    file = self.base
+    file = base
     file.extname = ".#{ext}"
     file
   end
@@ -154,8 +156,8 @@ end
 # Check the input file.
 begin
   File.open(infile) {}
-rescue => err
-  puts "#{Program}: #{err}"
+rescue SystemCallError => e
+  puts "#{PROGRAM}: #{e}"
   exit 2
 end
 
@@ -177,9 +179,10 @@ view(infile, mode) if not viewer_pid
     exit
   end
 end
-# If xdvi exits, this program should exit too.
+
+# If xdvi/evince exits, this program should exit too.
 Signal.trap("CLD") do
-  puts "#{Program}: viewer exited, so will I!"
+  puts "#{PROGRAM}: viewer exited, so will I!"
   clean(infile)
   exit
 end
@@ -195,6 +198,7 @@ dirs.each do |dir|
     # Only compile if a dependency of the input file has been modified
     file_path = (dir + ev.name).to_s
     next unless files.include? file_path
+
     puts "I: file #{ev.name} modified, compiling #{infile}..."
     compile(infile, mode)
     reload(infile, mode)