diff --git a/test/Microsoft.AspNetCore.Server.WebListener.FunctionalTests/ResponseTests.cs b/test/Microsoft.AspNetCore.Server.WebListener.FunctionalTests/ResponseTests.cs
index ad63957536..7203688118 100644
--- a/test/Microsoft.AspNetCore.Server.WebListener.FunctionalTests/ResponseTests.cs
+++ b/test/Microsoft.AspNetCore.Server.WebListener.FunctionalTests/ResponseTests.cs
@@ -97,7 +97,7 @@ namespace Microsoft.AspNetCore.Server.WebListener
             {
                 HttpResponseMessage response = await SendRequestAsync(address);
                 Assert.Equal(901, (int)response.StatusCode);
-                Assert.Equal(string.Empty, response.ReasonPhrase);
+                Assert.True(string.IsNullOrEmpty(response.ReasonPhrase)); // https://github.com/dotnet/corefx/issues/6721
                 Assert.Equal(string.Empty, await response.Content.ReadAsStringAsync());
             }
         }
diff --git a/test/Microsoft.Net.Http.Server.FunctionalTests/ResponseTests.cs b/test/Microsoft.Net.Http.Server.FunctionalTests/ResponseTests.cs
index 4e46f19ef7..e2266b330f 100644
--- a/test/Microsoft.Net.Http.Server.FunctionalTests/ResponseTests.cs
+++ b/test/Microsoft.Net.Http.Server.FunctionalTests/ResponseTests.cs
@@ -87,7 +87,7 @@ namespace Microsoft.Net.Http.Server
 
                 HttpResponseMessage response = await responseTask;
                 Assert.Equal(901, (int)response.StatusCode);
-                Assert.Equal(string.Empty, response.ReasonPhrase);
+                Assert.True(string.IsNullOrEmpty(response.ReasonPhrase)); // https://github.com/dotnet/corefx/issues/6721
                 Assert.Equal(string.Empty, await response.Content.ReadAsStringAsync());
             }
         }