diff --git a/CHANGELOG.md b/CHANGELOG.md
index f311bd28..d72ced23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - Made improvements to the experimental Realtime API. Please note this features area is currently under rapid development and not all changes may be reflected here. (commit_hash)
   - Several types have been renamed for consistency and clarity.
   - `ConversationRateLimitsUpdate` (previously `ConversationRateLimitsUpdatedUpdate`) now includes named `RequestDetails` and `TokenDetails` properties, mapping to the corresponding named items in the underlying `rate_limits` command payload.
+  - Serialization and deserialization of `ConversationToolChoice` literal values (such as `"required"`) is fixed
 
 ### Other Changes
 
diff --git a/api/OpenAI.netstandard2.0.cs b/api/OpenAI.netstandard2.0.cs
index 90fdcfcd..8fc8ec6e 100644
--- a/api/OpenAI.netstandard2.0.cs
+++ b/api/OpenAI.netstandard2.0.cs
@@ -2755,10 +2755,11 @@ public class ConversationToolChoice : IJsonModel<ConversationToolChoice>, IPersi
         BinaryData IPersistableModel<ConversationToolChoice>.Write(ModelReaderWriterOptions options);
     }
     public enum ConversationToolChoiceKind {
-        Auto = 0,
-        None = 1,
-        Required = 2,
-        Function = 3
+        Unknown = 0,
+        Auto = 1,
+        None = 2,
+        Required = 3,
+        Function = 4
     }
     public readonly partial struct ConversationToolKind : IEquatable<ConversationToolKind> {
         private readonly object _dummy;
diff --git a/src/Custom/RealtimeConversation/ConversationSessionOptions.cs b/src/Custom/RealtimeConversation/ConversationSessionOptions.cs
index a4b4d122..14f2abeb 100644
--- a/src/Custom/RealtimeConversation/ConversationSessionOptions.cs
+++ b/src/Custom/RealtimeConversation/ConversationSessionOptions.cs
@@ -26,7 +26,9 @@ public ConversationToolChoice ToolChoice
         get => ConversationToolChoice.FromBinaryData(_internalToolChoice);
         set
         {
-            _internalToolChoice = ModelReaderWriter.Write(value);
+            _internalToolChoice = value is not null
+                ? ModelReaderWriter.Write(value)
+                : null;
         }
     }
 
diff --git a/src/Custom/RealtimeConversation/ConversationToolChoice.Serialization.cs b/src/Custom/RealtimeConversation/ConversationToolChoice.Serialization.cs
index 267f18f4..d0367f25 100644
--- a/src/Custom/RealtimeConversation/ConversationToolChoice.Serialization.cs
+++ b/src/Custom/RealtimeConversation/ConversationToolChoice.Serialization.cs
@@ -29,7 +29,7 @@ internal static void SerializeConversationToolChoice(ConversationToolChoice inst
         }
         else
         {
-            writer.WriteStringValue(instance.Kind.ToString());
+            writer.WriteStringValue(instance.Kind.ToSerialString());
         }
     }
 
@@ -50,7 +50,7 @@ internal static ConversationToolChoice DeserializeConversationToolChoice(JsonEle
             return choiceObject switch
             {
                 InternalRealtimeToolChoiceFunctionObject => new(ConversationToolChoiceKind.Function, choiceObject),
-                _ => null,
+                _ => new(ConversationToolChoiceKind.Unknown, choiceObject),
             };
         }
         return null;
diff --git a/src/Custom/RealtimeConversation/ConversationToolChoice.cs b/src/Custom/RealtimeConversation/ConversationToolChoice.cs
index 58508579..10848654 100644
--- a/src/Custom/RealtimeConversation/ConversationToolChoice.cs
+++ b/src/Custom/RealtimeConversation/ConversationToolChoice.cs
@@ -26,4 +26,8 @@ internal ConversationToolChoice(ConversationToolChoiceKind choiceKind, InternalR
         Kind = choiceKind;
         _objectToolChoice = objectToolChoice;
     }
+
+    internal ConversationToolChoice() : this(ConversationToolChoiceKind.Unknown, null)
+    {
+    }
 }
\ No newline at end of file
diff --git a/src/Custom/RealtimeConversation/ConversationToolChoiceKind.cs b/src/Custom/RealtimeConversation/ConversationToolChoiceKind.cs
index ab6f431c..25a9a43c 100644
--- a/src/Custom/RealtimeConversation/ConversationToolChoiceKind.cs
+++ b/src/Custom/RealtimeConversation/ConversationToolChoiceKind.cs
@@ -8,11 +8,13 @@ namespace OpenAI.RealtimeConversation;
 [CodeGenModel("RealtimeToolChoiceLiteral")]
 public enum ConversationToolChoiceKind
 {
+    Unknown,
     [CodeGenMember("Auto")]
     Auto,
     [CodeGenMember("None")]
     None,
     [CodeGenMember("Required")]
     Required,
+    [CodeGenMember("Function")]
     Function,
 }
\ No newline at end of file
diff --git a/tests/RealtimeConversation/ConversationSmokeTests.cs b/tests/RealtimeConversation/ConversationSmokeTests.cs
index 136ec784..72bd3252 100644
--- a/tests/RealtimeConversation/ConversationSmokeTests.cs
+++ b/tests/RealtimeConversation/ConversationSmokeTests.cs
@@ -18,6 +18,35 @@ public class ConversationSmokeTests : ConversationTestFixtureBase
     public ConversationSmokeTests(bool isAsync) : base(isAsync)
     { }
 
+    [Test]
+    public void ToolChoiceSerializationInSessionOptionsWorks()
+    {
+        foreach((ConversationToolChoice toolChoice, string expected) in new (ConversationToolChoice, string)[]
+        {
+            (null, "{}"),
+            (ConversationToolChoice.CreateNoneToolChoice(), @"{""tool_choice"":""none""}"),
+            (ConversationToolChoice.CreateAutoToolChoice(), @"{""tool_choice"":""auto""}"),
+            (ConversationToolChoice.CreateRequiredToolChoice(), @"{""tool_choice"":""required""}"),
+            (ConversationToolChoice.CreateFunctionToolChoice("foo"), @"{""function"":{""name"":""foo""}")
+        })
+        {
+            ConversationSessionOptions options = new()
+            {
+                ToolChoice = toolChoice,
+            };
+            Assert.That(ModelReaderWriter.Write(options).ToString(), Does.Contain(expected));
+        }
+
+        ConversationToolChoice mrwToolChoice = ModelReaderWriter.Read<ConversationToolChoice>(
+            BinaryData.FromString("""
+                {
+                  "type":"some_manual_type"
+                }
+                """));
+        Assert.That(mrwToolChoice.Kind, Is.EqualTo(ConversationToolChoiceKind.Unknown));
+        Assert.That(ModelReaderWriter.Write(mrwToolChoice).ToString(), Does.Contain(@"""type"":""some_manual_type"""));
+    }
+    
     [Test]
     public void ItemCreation()
     {