diff --git a/app/models/user.rb b/app/models/user.rb
index f433a2d..ff07836 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,6 +1,6 @@
 class User < ActiveRecord::Base
 
-  USERNAME_FORMAT = /\A[a-z0-9][a-z0-9-]+[a-z0-9]\z/
+  USERNAME_FORMAT = /\A[a-zA-Z0-9][a-zA-Z0-9-]+[a-zA-Z0-9]\z/
 
   has_many :api_tokens, :dependent => :destroy
   has_many :asciicasts, :dependent => :destroy
@@ -11,7 +11,7 @@ class User < ActiveRecord::Base
   has_many :comments, :dependent => :destroy
 
   validates :username, presence: true
-  validates :username, uniqueness: { scope: :dummy },
+  validates :username, uniqueness: { scope: :dummy, case_sensitive: false },
                        format: { with: USERNAME_FORMAT },
                        length: { minimum: 3, maximum: 16 },
                        unless: :dummy
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 2fc091d..826f702 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -15,7 +15,7 @@ describe User do
   end
 
   describe "#valid?" do
-    let!(:existing_user) { create(:user) }
+    let!(:existing_user) { create(:user, username: 'the-user-name') }
     let(:user) { described_class.new }
 
     it { should validate_presence_of(:username) }
@@ -53,7 +53,7 @@ describe User do
       it { should allow_value('sick-ill').for(:username) }
       it { should allow_value('abc').for(:username) }
       it { should allow_value('s' * 16).for(:username) }
-      it { should_not allow_value('Sickill').for(:username) }
+      it { should allow_value('Sickill').for(:username) }
       it { should_not allow_value('sick.ill').for(:username) }
       it { should_not allow_value('-sickill').for(:username) }
       it { should_not allow_value('sickill-').for(:username) }
@@ -61,7 +61,7 @@ describe User do
       it { should_not allow_value('s' * 17).for(:username) }
 
       it "checks username uniqueness" do
-        user.username = existing_user.username
+        user.username = 'The-User-Name'
         user.valid?
         expect(user.errors[:username]).to_not be_empty
       end