diff --git a/src/GraphQL.Client.Serializer.SystemTextJson/ImmutableConverter.cs b/src/GraphQL.Client.Serializer.SystemTextJson/ImmutableConverter.cs
index 841b73d4..fa0a3f06 100644
--- a/src/GraphQL.Client.Serializer.SystemTextJson/ImmutableConverter.cs
+++ b/src/GraphQL.Client.Serializer.SystemTextJson/ImmutableConverter.cs
@@ -19,7 +19,7 @@ public override bool CanConvert(Type typeToConvert)
                 return false;
 
             var nullableUnderlyingType = Nullable.GetUnderlyingType(typeToConvert);
-            if (nullableUnderlyingType != null && nullableUnderlyingType.IsPrimitive)
+            if (nullableUnderlyingType != null && nullableUnderlyingType.IsValueType)
                 return false;
 
             bool result;
@@ -40,7 +40,7 @@ public override bool CanConvert(Type typeToConvert)
                     foreach (var parameter in parameters)
                     {
                         var hasMatchingProperty = properties.Any(p =>
-                            NameOfPropertyAndParameter.Matches(p.Name, parameter.Name, typeToConvert.IsAnonymous()));
+                                                                     NameOfPropertyAndParameter.Matches(p.Name, parameter.Name, typeToConvert.IsAnonymous()));
                         if (!hasMatchingProperty)
                         {
                             result = false;
@@ -90,7 +90,7 @@ public override object Read(ref Utf8JsonReader reader, Type typeToConvert, JsonS
             {
                 var parameterInfo = parameters[index];
                 var value = valueOfProperty.First(prop =>
-                    NameOfPropertyAndParameter.Matches(prop.Key.Name, parameterInfo.Name, typeToConvert.IsAnonymous())).Value;
+                                                      NameOfPropertyAndParameter.Matches(prop.Key.Name, parameterInfo.Name, typeToConvert.IsAnonymous())).Value;
 
                 parameterValues[index] = value;
             }
@@ -120,6 +120,7 @@ public override void Write(Utf8JsonWriter writer, object value, JsonSerializerOp
                 if (!(converter is ImmutableConverter))
                     strippedOptions.Converters.Add(converter);
             }
+
             JsonSerializer.Serialize(writer, value, strippedOptions);
         }
 
diff --git a/tests/GraphQL.Client.Serializer.Tests/BaseSerializerTest.cs b/tests/GraphQL.Client.Serializer.Tests/BaseSerializerTest.cs
index e8bd28db..53cba0c1 100644
--- a/tests/GraphQL.Client.Serializer.Tests/BaseSerializerTest.cs
+++ b/tests/GraphQL.Client.Serializer.Tests/BaseSerializerTest.cs
@@ -58,13 +58,15 @@ public async void DeserializeFromUtf8StreamTest(string json, IGraphQLResponse ex
             var jsonBytes = Encoding.UTF8.GetBytes(json);
             await using var ms = new MemoryStream(jsonBytes);
             var response = await DeserializeToUnknownType(expectedResponse.Data?.GetType() ?? typeof(object), ms);
+
             //var response = await Serializer.DeserializeFromUtf8StreamAsync<object>(ms, CancellationToken.None);
 
             response.Data.Should().BeEquivalentTo(expectedResponse.Data, options => options.WithAutoConversion());
 
             if (expectedResponse.Errors is null)
                 response.Errors.Should().BeNull();
-            else {
+            else
+            {
                 using (new AssertionScope())
                 {
                     response.Errors.Should().NotBeNull();
@@ -95,7 +97,7 @@ public async Task<IGraphQLResponse> DeserializeToUnknownType(Type dataType, Stre
         {
             MethodInfo mi = Serializer.GetType().GetMethod("DeserializeFromUtf8StreamAsync", BindingFlags.Instance | BindingFlags.Public);
             MethodInfo mi2 = mi.MakeGenericMethod(dataType);
-            var task = (Task) mi2.Invoke(Serializer, new object[] { stream, CancellationToken.None });
+            var task = (Task)mi2.Invoke(Serializer, new object[] { stream, CancellationToken.None });
             await task;
             var resultProperty = task.GetType().GetProperty("Result", BindingFlags.Public | BindingFlags.Instance);
             var result = resultProperty.GetValue(task);
@@ -105,9 +107,8 @@ public async Task<IGraphQLResponse> DeserializeToUnknownType(Type dataType, Stre
         [Fact]
         public async void CanDeserializeExtensions()
         {
-
             var response = await ChatClient.SendQueryAsync(new GraphQLRequest("query { extensionsTest }"),
-                    () => new { extensionsTest = "" })
+                                                           () => new { extensionsTest = "" })
                 ;
 
             response.Errors.Should().NotBeNull();
@@ -134,8 +135,8 @@ query Droid($id: String!) {
 				    name
 				  }
 				}",
-                new { id = id.ToString() },
-                "Human");
+                                                    new { id = id.ToString() },
+                                                    "Human");
 
             var response = await StarWarsClient.SendQueryAsync(graphQLRequest, () => new { Human = new { Name = string.Empty } });
 
@@ -152,7 +153,6 @@ public async void CanDoSerializationWithPredefinedTypes()
             Assert.Equal(message, response.Data.AddMessage.Content);
         }
 
-        
         public class WithNullable
         {
             public int? NullableInt { get; set; }
@@ -172,5 +172,25 @@ public void CanSerializeNullableInt()
 
             action.Should().NotThrow();
         }
+
+        public class WithNullableStruct
+        {
+            public DateTime? NullableStruct { get; set; }
+        }
+
+        [Fact]
+        public void CanSerializeNullableStruct()
+        {
+            Action action = () => Serializer.SerializeToString(new GraphQLRequest
+            {
+                Query = "{}",
+                Variables = new WithNullableStruct
+                {
+                    NullableStruct = DateTime.Now
+                }
+            });
+
+            action.Should().NotThrow();
+        }
     }
 }