diff --git a/lib/gcovinator.rb b/lib/gcovinator.rb
index 26b9156..9faf1a9 100644
--- a/lib/gcovinator.rb
+++ b/lib/gcovinator.rb
@@ -1,5 +1,14 @@
 require_relative "gcovinator/version"
 
 module Gcovinator
-  # Your code goes here...
+
+  class << self
+
+    def run(build_dir, source_dirs, files, output_dir)
+      source_dirs = ["."] if source_dirs.empty?
+      files = Dir["#{build_dir}/**/*.gcda"] if files.empty?
+    end
+
+  end
+
 end
diff --git a/lib/gcovinator/cli.rb b/lib/gcovinator/cli.rb
index db901f9..25880fc 100644
--- a/lib/gcovinator/cli.rb
+++ b/lib/gcovinator/cli.rb
@@ -5,10 +5,12 @@ module Gcovinator
   module Cli
 
     class << self
+
       def run(argv)
         argv = argv.dup
         build_dir = "."
         source_dirs = []
+        output_dir = "coverage"
 
         OptionParser.new do |opts|
 
@@ -16,7 +18,7 @@ module Gcovinator
 
           opts.separator ""
           opts.separator "Pass paths to .gcda files as FILES."
-          opts.separator "If no FILES are specified, gcovinator looks for all .gcda files recursively under the build directory"
+          opts.separator "If no FILES are specified, gcovinator looks for all .gcda files recursively under the build directory."
           opts.separator ""
           opts.separator "Options:"
 
@@ -24,6 +26,15 @@ module Gcovinator
             build_dir = b
           end
 
+          opts.on_tail("-h", "--help", "Show this help.") do
+            puts opts
+            exit 0
+          end
+
+          opts.on("-o OUTPUTDIR", "--output-dir OUTPUTDIR", "Specify output directory. HTML reports will be written to this directory. Defaults to 'coverage' if not specified.") do |o|
+            output_dir = o
+          end
+
           opts.on("-s SRCDIR", "--source-dir SRCDIR", "Specify a source directory. Reports will only be generated for sources under a specified source directory. Multiple source directories may be specified. Defaults to '.' if not specified.") do |s|
             source_dirs << s
           end
@@ -33,14 +44,11 @@ module Gcovinator
             exit 0
           end
 
-          opts.on_tail("-h", "--help", "Show this help.") do
-            puts opts
-            exit 0
-          end
-
         end.parse!(argv)
 
+        Gcovinator.run(build_dir, source_dirs, argv)
       end
+
     end
 
   end