diff --git a/src/Umbraco.Tests/Routing/ContentFinderByNiceUrlWithDomainsTests.cs b/src/Umbraco.Tests/Routing/ContentFinderByNiceUrlWithDomainsTests.cs
index 3dcc127f86..9b23b1c5e8 100644
--- a/src/Umbraco.Tests/Routing/ContentFinderByNiceUrlWithDomainsTests.cs
+++ b/src/Umbraco.Tests/Routing/ContentFinderByNiceUrlWithDomainsTests.cs
@@ -145,7 +145,7 @@ namespace Umbraco.Tests.Routing
 		[TestCase("http://domain1.com/fr/1001-2-1", 100121, "fr-FR")]
 		[TestCase("http://domain1.com/1001-3", 10013, "en-US")]
 
-		[TestCase("http://domain2.com/1002", 1002, "en-US")]
+		[TestCase("http://domain2.com/1002", 1002, null)]
 
 		[TestCase("http://domain3.com/", 1003, "en-US")]
 		[TestCase("http://domain3.com/en", 10031, "en-US")]
@@ -155,12 +155,15 @@ namespace Umbraco.Tests.Routing
 		[TestCase("http://domain3.com/1003-3", 10033, "en-US")]
 
 		[TestCase("https://domain1.com/", 1001, "en-US")]
-		[TestCase("https://domain3.com/", 1001, "en-US")] // because domain3 is explicitely set on http
+		[TestCase("https://domain3.com/", 1001, null)] // because domain3 is explicitely set on http
 
 		public void Lookup_NestedDomains(string url, int expectedId, string expectedCulture)
 		{
 			SetDomains4();
 
+            // defaults depend on test environment
+            expectedCulture = expectedCulture ?? System.Threading.Thread.CurrentThread.CurrentUICulture.Name;
+
             SettingsForTests.HideTopLevelNodeFromPath = true;
 
 			var routingContext = GetRoutingContext(url);
diff --git a/src/Umbraco.Tests/Routing/DomainsAndCulturesTests.cs b/src/Umbraco.Tests/Routing/DomainsAndCulturesTests.cs
index 9042bbca53..0cfd4a8b24 100644
--- a/src/Umbraco.Tests/Routing/DomainsAndCulturesTests.cs
+++ b/src/Umbraco.Tests/Routing/DomainsAndCulturesTests.cs
@@ -179,7 +179,7 @@ namespace Umbraco.Tests.Routing
         [TestCase("http://domain1.com/fr", "fr-FR", 10012)] // domain takes over local wildcard at 10012
         [TestCase("http://domain1.com/fr/1001-2-1", "fr-FR", 100121)] // domain takes over local wildcard at 10012
 
-        [TestCase("/1003", "en-US", 1003)] // default culture (no domain)
+        [TestCase("/1003", null, 1003)] // default culture (no domain)
         [TestCase("/1003/1003-1", "nl-NL", 10031)] // wildcard on 10031 applies
         [TestCase("/1003/1003-1/1003-1-1", "nl-NL", 100311)] // wildcard on 10031 applies
         #endregion
@@ -187,6 +187,9 @@ namespace Umbraco.Tests.Routing
         {
             SetDomains2();
 
+            // defaults depend on test environment
+            expectedCulture = expectedCulture ?? System.Threading.Thread.CurrentThread.CurrentUICulture.Name;
+
             var routingContext = GetRoutingContext(inputUrl);
             var url = routingContext.UmbracoContext.CleanedUmbracoUrl; //very important to use the cleaned up umbraco url
             var pcr = new PublishedContentRequest(url, routingContext);