diff --git a/lib/reek/source/source_locator.rb b/lib/reek/source/source_locator.rb
index <HASH>..<HASH> 100644
--- a/lib/reek/source/source_locator.rb
+++ b/lib/reek/source/source_locator.rb
@@ -19,7 +19,7 @@ module Reek
 
       def all_ruby_source_files(paths)
         paths.map do |path|
-          if test 'd', path
+          if test ?d, path
             all_ruby_source_files(Dir["#{path}/**/*.rb"])
           else
             path
@@ -29,7 +29,7 @@ module Reek
 
       def valid_paths
         all_ruby_source_files(@paths).select do |path|
-          if test 'f', path
+          if test ?f, path
             true
           else
             $stderr.puts "Error: No such file - #{path}"
fix the test method call to pass integer over string