diff --git a/build/NuSpecs/tools/Web.config.install.xdt b/build/NuSpecs/tools/Web.config.install.xdt
index 315fbf8890..5ee5ed32c6 100644
--- a/build/NuSpecs/tools/Web.config.install.xdt
+++ b/build/NuSpecs/tools/Web.config.install.xdt
@@ -24,6 +24,7 @@
     <add key="owin:appStartup" value="UmbracoDefaultOwinStartup" xdt:Locator="Match(key)" xdt:Transform="InsertIfMissing" />
 	<add key="Umbraco.ModelsBuilder.Enable" value="false" xdt:Locator="Match(key)" xdt:Transform="InsertIfMissing" />
 	<add key="Umbraco.ModelsBuilder.ModelsMode" value="Nothing" xdt:Locator="Match(key)" xdt:Transform="InsertIfMissing" />
+	<add key="umbracoDefaultUILanguage" value="en-US" xdt:Locator="Match(key)" xdt:Transform="SetAttributes(value)" />
   </appSettings>
 
   <umbracoConfiguration xdt:Transform="InsertIfMissing">
diff --git a/src/Umbraco.Core/Persistence/Migrations/Initial/BaseDataCreation.cs b/src/Umbraco.Core/Persistence/Migrations/Initial/BaseDataCreation.cs
index 3ff8ecaa56..c6fadc1dd8 100644
--- a/src/Umbraco.Core/Persistence/Migrations/Initial/BaseDataCreation.cs
+++ b/src/Umbraco.Core/Persistence/Migrations/Initial/BaseDataCreation.cs
@@ -169,7 +169,7 @@ namespace Umbraco.Core.Persistence.Migrations.Initial
 
         private void CreateUmbracoUserData()
         {
-            _database.Insert("umbracoUser", "id", false, new UserDto { Id = 0, Disabled = false, NoConsole = false, UserName = "Administrator", Login = "admin", Password = "default", Email = "", UserLanguage = "en", CreateDate = DateTime.Now, UpdateDate = DateTime.Now });
+            _database.Insert("umbracoUser", "id", false, new UserDto { Id = 0, Disabled = false, NoConsole = false, UserName = "Administrator", Login = "admin", Password = "default", Email = "", UserLanguage = "en-US", CreateDate = DateTime.Now, UpdateDate = DateTime.Now });
         }
         
         private void CreateUmbracoUserGroupData()
diff --git a/src/Umbraco.Web.UI/web.Template.config b/src/Umbraco.Web.UI/web.Template.config
index cc06d4145d..ee8d98cae3 100644
--- a/src/Umbraco.Web.UI/web.Template.config
+++ b/src/Umbraco.Web.UI/web.Template.config
@@ -48,7 +48,7 @@
 		<add key="umbracoHideTopLevelNodeFromPath" value="true" />
 		<add key="umbracoUseDirectoryUrls" value="true" />
 		<add key="umbracoTimeOutInMinutes" value="20" />
-		<add key="umbracoDefaultUILanguage" value="en" />
+		<add key="umbracoDefaultUILanguage" value="en-US" />
 		<add key="umbracoUseSSL" value="false" />
 
 		<add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />