diff --git a/test/MockHttp.Tests/Extensions/HttpContentExtensionsTests.cs b/test/MockHttp.Tests/Extensions/HttpContentExtensionsTests.cs
index e35e2346..6fe68b94 100644
--- a/test/MockHttp.Tests/Extensions/HttpContentExtensionsTests.cs
+++ b/test/MockHttp.Tests/Extensions/HttpContentExtensionsTests.cs
@@ -68,7 +68,7 @@ static object[] CreateTestCase(HttpContent content, string expectedData)
         yield return CreateTestCase(new StringContent(data), data);
         yield return CreateTestCase(new ByteArrayContent(buffer), data);
         yield return CreateTestCase(new StreamContent(new MemoryStream(buffer)), data);
-        yield return CreateTestCase(new FormUrlEncodedContent(new Dictionary<string, string> { { "key", data } }), "key=" + Uri.EscapeDataString(data));
+        yield return CreateTestCase(new FormUrlEncodedContent(new[] { new KeyValuePair<string?, string?>("key", data) }), "key=" + Uri.EscapeDataString(data));
 
         var mpc = new MultipartContent("subtype", "boundary") { new StringContent(data) };
         yield return CreateTestCase(mpc, "--boundary\r\nContent-Type: text/plain; charset=utf-8\r\n\r\n<b>data</b>\r\n--boundary--\r\n");
diff --git a/test/MockHttp.Tests/Extensions/RequestMatchingExtensionsTests.cs b/test/MockHttp.Tests/Extensions/RequestMatchingExtensionsTests.cs
index 2f4c048b..e3a010c0 100644
--- a/test/MockHttp.Tests/Extensions/RequestMatchingExtensionsTests.cs
+++ b/test/MockHttp.Tests/Extensions/RequestMatchingExtensionsTests.cs
@@ -248,7 +248,7 @@ public async Task When_configuring_formData_with_null_value_should_match()
                 RequestUri = new Uri("http://127.0.0.1"),
                 Content = new FormUrlEncodedContent(new[]
                 {
-                    new KeyValuePair<string, string>("key", null!)
+                    new KeyValuePair<string?, string?>("key", null!)
                 })
             };
 
@@ -269,7 +269,7 @@ public async Task When_configuring_formData_with_empty_value_should_match()
                 RequestUri = new Uri("http://127.0.0.1"),
                 Content = new FormUrlEncodedContent(new[]
                 {
-                    new KeyValuePair<string, string>("key", string.Empty)
+                    new KeyValuePair<string?, string?>("key", string.Empty)
                 })
             };