diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c111b33
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.gem
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..debc11c
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,8 @@
+require 'rake/testtask'
+
+Rake::TestTask.new do |t|
+  t.libs << 'test'
+end
+
+desc "Run tests"
+task :default => :test
diff --git a/lib/sinatra/browserid.rb b/lib/sinatra/browserid.rb
index 0ceda52..98aa60c 100644
--- a/lib/sinatra/browserid.rb
+++ b/lib/sinatra/browserid.rb
@@ -4,6 +4,8 @@
 require 'json'
 require 'url_safe_base64'
 require 'jwt'
+require 'simpleidn'
+require 'ipaddr'
 require "sinatra/base"
 require 'sinatra/browserid/helpers'
 require 'sinatra/browserid/template'
@@ -44,7 +46,7 @@ def self.registered(app)
                       id_token["exp"] > Time.now.to_i &&
                       id_token["email_verified"] &&
                       id_token["nonce"] == session[:nonce])
-                          session[:browserid_email] = id_token["email"]
+                          session[:browserid_email] = id_token['sub']
                           session.delete(:nonce)
                           if session['redirect_url']
                             redirect session['redirect_url']
diff --git a/lib/sinatra/browserid/helpers.rb b/lib/sinatra/browserid/helpers.rb
index 05f1b0d..3d27c5c 100644
--- a/lib/sinatra/browserid/helpers.rb
+++ b/lib/sinatra/browserid/helpers.rb
@@ -28,6 +28,28 @@ def authorized_email
         session[:browserid_email]
       end
 
+      # Normalize the email like the broker will do it, see
+      # https://github.com/portier/portier.github.io/blob/master/specs/Email-Normalization.md
+      def normalize_email(email)
+        begin
+            user, domain = email.split("@")
+            if user == nil or user.empty?
+                raise ArgumentError.new('user part must not be empty')  
+            end 
+            user = user.downcase
+            domain = SimpleIDN.to_ascii(domain).downcase
+            begin
+                IPAddr.new(domain)
+            rescue
+                # if domain could not be parsed as IP we are good
+                return user + "@" + domain
+            end
+            raise ArgumentError.new('domain must not be an IP')  
+        rescue Exception => e
+            raise ArgumentError, 'Not a valid email adress: ' + e.message
+        end
+      end
+
       # Returns the HTML to render the Persona login form.
       # Optionally takes a URL parameter for where the user should
       # be redirected to after the assert POST back.
diff --git a/sinatra-portier.gemspec b/sinatra-portier.gemspec
index cc75455..654139f 100644
--- a/sinatra-portier.gemspec
+++ b/sinatra-portier.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name = "sinatra-portier"
-  s.version = "1.4.0"
+  s.version = "1.5.0"
 
   s.authors = ["Pete Fritchman", "Malte Paskuda"]
   s.email = ["malte@paskuda.biz"]
@@ -17,4 +17,7 @@ Gem::Specification.new do |s|
   s.add_dependency("sinatra", ">= 1.1.0")
   s.add_dependency("jwt", ">= 1.5.4")
   s.add_dependency("url_safe_base64", ">= 0.2.2")
+  s.add_dependency("simpleidn", ">= 0.0.9")
+
+  s.required_ruby_version(">= 2.4.0")
 end
diff --git a/test/test_normalization.rb b/test/test_normalization.rb
new file mode 100644
index 0000000..94c6bf6
--- /dev/null
+++ b/test/test_normalization.rb
@@ -0,0 +1,31 @@
+require 'minitest/autorun'
+require 'sinatra/portier.rb'
+
+
+class NormalizationTest < Minitest::Test
+    include Sinatra::BrowserID::Helpers
+    def test_valid
+        assert_equal("example.foo+bar@example.com", normalize_email("example.foo+bar@example.com"))
+        assert_equal("example.foo+bar@example.com", normalize_email("EXAMPLE.FOO+BAR@EXAMPLE.COM"))
+        assert_equal("björn@xn--gteborg-90a.test", normalize_email("BJÖRN@göteborg.test"))
+        assert_equal("i̇ⅲ@xn--iiii-qwc.example", normalize_email("İⅢ@İⅢ.example"))
+    end
+
+    def test_invalid
+        assert_raises("ArgumentError") { 
+            normalize_email("foo")
+        }
+        assert_raises("ArgumentError") { 
+            normalize_email("foo@")
+        }
+        assert_raises("ArgumentError") {     
+            normalize_email("@foo.example")
+        }
+        assert_raises("ArgumentError") { 
+            normalize_email("foo@127.0.0.1")
+        }
+        assert_raises("ArgumentError") { 
+            normalize_email("foo@[::1]")
+        }
+    end
+end