diff --git a/src/libraries/System.Net.HttpListener/tests/InvalidClientRequestTests.cs b/src/libraries/System.Net.HttpListener/tests/InvalidClientRequestTests.cs
index a9703669b6bdbc..8c8ba02de4b8e3 100644
--- a/src/libraries/System.Net.HttpListener/tests/InvalidClientRequestTests.cs
+++ b/src/libraries/System.Net.HttpListener/tests/InvalidClientRequestTests.cs
@@ -74,8 +74,11 @@ public static IEnumerable<object[]> InvalidRequest_TestData()
             yield return new object[] { "GET {path} HTTP/1.1", null, new string[] { "Content-Length: -9223372036854775809" }, "\r\n", "Bad Request" };
 
             yield return new object[] { "GET {path} HTTP/1.1", null, new string[] { "Content-Length: 1", "Content-Length: 2" }, "\r\n", "Bad Request" };
-            yield return new object[] { "POST {path} HTTP/1.1", null, new string[] { "Content-Length: 9223372036854775808" }, "\r\n", "Bad Request" }; // long.MaxValue + 1
-            yield return new object[] { "POST {path} HTTP/1.1", null, new string[] { "Content-Length: 18446744073709551615" }, "\r\n", "Bad Request" }; // ulong.MaxValue
+            if (Helpers.IsManagedImplementation)
+            {
+                yield return new object[] { "POST {path} HTTP/1.1", null, new string[] { "Content-Length: 9223372036854775808" }, "\r\n", "Bad Request" }; // long.MaxValue + 1
+                yield return new object[] { "POST {path} HTTP/1.1", null, new string[] { "Content-Length: 18446744073709551615" }, "\r\n", "Bad Request" }; // ulong.MaxValue
+            }
 
             yield return new object[] { "GET {path} HTTP/1.1", null, new string[] { "Transfer-Encoding: garbage" }, "\r\n", "Not Implemented" };
             yield return new object[] { "POST {path} HTTP/1.1", null, new string[] { "Transfer-Encoding: garbage" }, "\r\n", "Not Implemented" };