diff --git a/app/models/user.rb b/app/models/user.rb
index 6a5411b..8efae30 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -205,6 +205,7 @@ class User < ActiveRecord::Base
       u.projects_limit = Gitlab.config.gitlab.default_projects_limit
       u.can_create_group = Gitlab.config.gitlab.default_can_create_group
       u.can_create_team = Gitlab.config.gitlab.default_can_create_team
+      u.theme_id = Gitlab::Theme::MARS
     end
   end
 
diff --git a/lib/gitlab/theme.rb b/lib/gitlab/theme.rb
index 7f83386..8960416 100644
--- a/lib/gitlab/theme.rb
+++ b/lib/gitlab/theme.rb
@@ -1,12 +1,18 @@
 module Gitlab
   class Theme
+    BASIC  = 1
+    MARS   = 2
+    MODERN = 3
+    GRAY   = 4
+    COLOR  = 5
+
     def self.css_class_by_id(id)
       themes = {
-        1 => "ui_basic",
-        2 => "ui_mars",
-        3 => "ui_modern",
-        4 => "ui_gray",
-        5 => "ui_color"
+        BASIC  => "ui_basic",
+        MARS   => "ui_mars",
+        MODERN => "ui_modern",
+        GRAY   => "ui_gray",
+        COLOR  => "ui_color"
       }
 
       id ||= 1
--
libgit2 0.21.2