diff --git a/tools/list-untested.rb b/tools/list-untested.rb
index 1ca7817..fb89e7b 100644
--- a/tools/list-untested.rb
+++ b/tools/list-untested.rb
@@ -1,12 +1,18 @@
+require 'pathname'
+
+def main
+  Dir.chdir Pathname.new($PROGRAM_NAME).realpath.dirname.dirname + 'test'
+  test_sh = File.read('test_cbc.sh')
+  tested = test_sh.scan(/[\$\w\-]+\.cb/).reject {|n| /\$/ =~ n } +
+           test_sh.scan(%r<\./[\w\-]+>).map {|n| File.basename(n) + '.cb' }
+  tested = tested.uniq
+  print_list Dir.glob('*.cb') - tested
+end
+
 def print_list(list)
   list.sort.each do |name|
     puts name
   end
 end
 
-test_sh = File.read('test_cbc.sh')
-tested = test_sh.scan(/[\$\w\-]+\.cb/).reject {|n| /\$/ =~ n } +
-         test_sh.scan(%r<\./[\w\-]+>).map {|n| File.basename(n) + '.cb' }
-tested = tested.uniq
-
-print_list Dir.glob('*.cb') - tested
+main