diff --git a/src/Servers/Kestrel/test/FunctionalTests/RequestTests.cs b/src/Servers/Kestrel/test/FunctionalTests/RequestTests.cs
index c41212972d..96083d7ae8 100644
--- a/src/Servers/Kestrel/test/FunctionalTests/RequestTests.cs
+++ b/src/Servers/Kestrel/test/FunctionalTests/RequestTests.cs
@@ -1274,7 +1274,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
                 }
             }
 
-            await Assert.ThrowsAsync<TaskCanceledException>(async () => await readTcs.Task);
+            var thrownEx = await Assert.ThrowsAnyAsync<Exception>(async () => await readTcs.Task);
+
+            // https://github.com/aspnet/AspNetCore-Internal/issues/1521
+            // In more recent versions of Kestrel, we expect this to always be a TaskCanceledException,
+            // but without the changes in https://github.com/aspnet/KestrelHttpServer/pull/2844, this is flaky.
+            Assert.True(thrownEx is TaskCanceledException || thrownEx is IOException, $"{thrownEx} is neither a TaskCanceledException nor IOException.");
 
             // The cancellation token for only the last request should be triggered.
             var abortedRequestId = await registrationTcs.Task;