diff --git a/app/models/locomotive/extensions/site/subdomain_domains.rb b/app/models/locomotive/extensions/site/subdomain_domains.rb
index 46f1df2a..71963b5f 100644
--- a/app/models/locomotive/extensions/site/subdomain_domains.rb
+++ b/app/models/locomotive/extensions/site/subdomain_domains.rb
@@ -37,9 +37,13 @@ module Locomotive
 
         module InstanceMethods
 
+          def subdomain=(subdomain)
+            super(subdomain.try(:downcase))
+          end
+
           def domains=(array)
             array.reject!(&:blank?)
-            array = [] if array.blank?; super(array)
+            array = [] if array.blank?; super(array.map(&:downcase))
           end
 
           def add_subdomain_to_domains
@@ -84,4 +88,4 @@ module Locomotive
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/spec/models/locomotive/extensions/site/subdomain_domains_spec.rb b/spec/models/locomotive/extensions/site/subdomain_domains_spec.rb
new file mode 100644
index 00000000..f9fb33e4
--- /dev/null
+++ b/spec/models/locomotive/extensions/site/subdomain_domains_spec.rb
@@ -0,0 +1,23 @@
+require 'spec_helper'
+
+describe Locomotive::Extensions::Site::SubdomainDomains do
+  describe '#subdomain=' do
+    let(:site) { Locomotive::Site.new }
+
+    it 'downcases the subdomain' do
+      site.subdomain = 'MiXeDCaSe'
+
+      site.subdomain.should == 'mixedcase'
+    end
+  end
+
+  describe '#domains=' do
+    let(:site) { Locomotive::Site.new }
+
+    it 'downcases the domains' do
+      site.domains = ['FIRST.com', 'second.com', 'THIRD.com']
+
+      site.domains.should == ['first.com', 'second.com', 'third.com']
+    end
+  end
+end