diff --git a/test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/AuthenticationTests.cs b/test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/AuthenticationTests.cs
index 7a4a184087..b1fdb0ed19 100644
--- a/test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/AuthenticationTests.cs
+++ b/test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/AuthenticationTests.cs
@@ -353,7 +353,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             }
         }
 
-        [ConditionalTheory]
+        [ConditionalTheory(Skip = "https://github.com/aspnet/HttpSysServer/issues/439")]
         [InlineData(AuthenticationSchemes.Negotiate)]
         [InlineData(AuthenticationSchemes.NTLM)]
         // [InlineData(AuthenticationSchemes.Digest)] // Not implemented