diff --git a/packages/nitrogen/src/syntax/createType.ts b/packages/nitrogen/src/syntax/createType.ts
index cadd9ce8f..e05fec6a4 100644
--- a/packages/nitrogen/src/syntax/createType.ts
+++ b/packages/nitrogen/src/syntax/createType.ts
@@ -208,11 +208,18 @@ export function createType(type: TSMorphType, isOptional: boolean): Type {
       )
       return new EnumType(typename, enumDeclaration)
     } else if (type.isUnion()) {
-      // It is some kind of union - either full of strings (then it's an enum, or different types, then it's a Variant)
-      const isEnumUnion = type.getUnionTypes().every((t) => t.isStringLiteral())
+      // It is some kind of union;
+      // - of string literals (then it's an enum)
+      // - of type `T | undefined` (then it's just optional `T`)
+      // - of different types (then it's a variant `A | B | C`)
+      const types = type.getUnionTypes()
+      const nonNullTypes = types.filter(
+        (t) => !t.isNull() && !t.isUndefined() && !t.isVoid()
+      )
+      const isEnumUnion = nonNullTypes.every((t) => t.isStringLiteral())
       if (isEnumUnion) {
         // It consists only of string literaly - that means it's describing an enum!
-        const symbol = type.getAliasSymbol()
+        const symbol = type.getNonNullableType().getAliasSymbol()
         if (symbol == null) {
           // If there is no alias, it is an inline union instead of a separate type declaration!
           throw new Error(
@@ -258,9 +265,7 @@ export function createType(type: TSMorphType, isOptional: boolean): Type {
         `Anonymous objects cannot be represented in C++! Extract "${type.getText()}" to a separate interface/type declaration.`
       )
     } else if (type.isStringLiteral()) {
-      throw new Error(
-        `String literal ${type.getText()} cannot be represented in C++ because it is ambiguous between a string and a discriminating union enum.`
-      )
+      return new StringType()
     } else {
       throw new Error(
         `The TypeScript type "${type.getText()}" cannot be represented in C++!`
diff --git a/packages/nitrogen/src/syntax/types/EnumType.ts b/packages/nitrogen/src/syntax/types/EnumType.ts
index 3395654a3..8a2278548 100644
--- a/packages/nitrogen/src/syntax/types/EnumType.ts
+++ b/packages/nitrogen/src/syntax/types/EnumType.ts
@@ -50,24 +50,27 @@ export class EnumType implements Type {
     } else {
       // It's a TS union '..' | '..'
       this.jsType = 'union'
-      this.enumMembers = declaration.getUnionTypes().map((t, i) => {
-        if (t.isStringLiteral()) {
-          const literalValue = t.getLiteralValueOrThrow()
-          if (typeof literalValue !== 'string')
+      this.enumMembers = declaration
+        .getNonNullableType()
+        .getUnionTypes()
+        .map((t, i) => {
+          if (t.isStringLiteral()) {
+            const literalValue = t.getLiteralValueOrThrow()
+            if (typeof literalValue !== 'string')
+              throw new Error(
+                `${enumName}: Value "${literalValue}" is not a string - it is ${typeof literalValue}!`
+              )
+            return {
+              name: escapeCppName(literalValue).toUpperCase(),
+              value: i,
+              stringValue: literalValue,
+            }
+          } else {
             throw new Error(
-              `${enumName}: Value "${literalValue}" is not a string - it is ${typeof literalValue}!`
+              `${enumName}: Value "${t.getText()}" is not a string literal - it cannot be represented in a C++ enum!`
             )
-          return {
-            name: escapeCppName(literalValue).toUpperCase(),
-            value: i,
-            stringValue: literalValue,
           }
-        } else {
-          throw new Error(
-            `${enumName}: Value "${t.getText()}" is not a string literal - it cannot be represented in a C++ enum!`
-          )
-        }
-      })
+        })
       this.declarationFile = createCppUnion(enumName, this.enumMembers)
     }
   }
diff --git a/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.cpp b/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.cpp
index 1c3f893f8..c2363a0e7 100644
--- a/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.cpp
+++ b/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.cpp
@@ -176,5 +176,9 @@ namespace margelo::nitro::image {
     static const auto method = _javaPart->getClass()->getMethod<void(jni::alias_ref<JFunc_void_Person::javaobject> /* callback */)>("addOnPersonBornListener");
     method(_javaPart, JFunc_void_Person::fromCpp(callback));
   }
+  void JHybridKotlinTestObjectSpec::something1(std::optional<Powertrain> optional) {
+    static const auto method = _javaPart->getClass()->getMethod<void(jni::alias_ref<JPowertrain> /* optional */)>("something1");
+    method(_javaPart, optional.has_value() ? JPowertrain::fromCpp(optional.value()) : nullptr);
+  }
 
 } // namespace margelo::nitro::image
diff --git a/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.hpp b/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.hpp
index 179e99c1e..b12e8888c 100644
--- a/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.hpp
+++ b/packages/react-native-nitro-image/nitrogen/generated/android/c++/JHybridKotlinTestObjectSpec.hpp
@@ -56,6 +56,7 @@ namespace margelo::nitro::image {
     std::future<void> asyncTest() override;
     std::shared_ptr<AnyMap> createMap() override;
     void addOnPersonBornListener(const std::function<void(const Person& /* p */)>& callback) override;
+    void something1(std::optional<Powertrain> optional) override;
 
   private:
     friend HybridBase;
diff --git a/packages/react-native-nitro-image/nitrogen/generated/android/kotlin/com/margelo/nitro/image/HybridKotlinTestObjectSpec.kt b/packages/react-native-nitro-image/nitrogen/generated/android/kotlin/com/margelo/nitro/image/HybridKotlinTestObjectSpec.kt
index f35676636..7d4211d28 100644
--- a/packages/react-native-nitro-image/nitrogen/generated/android/kotlin/com/margelo/nitro/image/HybridKotlinTestObjectSpec.kt
+++ b/packages/react-native-nitro-image/nitrogen/generated/android/kotlin/com/margelo/nitro/image/HybridKotlinTestObjectSpec.kt
@@ -88,6 +88,10 @@ abstract class HybridKotlinTestObjectSpec: HybridObject() {
     val result = addOnPersonBornListener(callback.toLambda())
     return result
   }
+  
+  @DoNotStrip
+  @Keep
+  abstract fun something1(optional: Powertrain?): Unit
 
   private external fun initHybrid(): HybridData
 
diff --git a/packages/react-native-nitro-image/nitrogen/generated/ios/NitroImage-Swift-Cxx-Bridge.hpp b/packages/react-native-nitro-image/nitrogen/generated/ios/NitroImage-Swift-Cxx-Bridge.hpp
index becbaeb2f..c42f124f3 100644
--- a/packages/react-native-nitro-image/nitrogen/generated/ios/NitroImage-Swift-Cxx-Bridge.hpp
+++ b/packages/react-native-nitro-image/nitrogen/generated/ios/NitroImage-Swift-Cxx-Bridge.hpp
@@ -556,5 +556,13 @@ namespace margelo::nitro::image::bridge::swift {
   inline std::shared_ptr<Func_void_Person_Wrapper> share_Func_void_Person(const Func_void_Person& value) {
     return std::make_shared<Func_void_Person_Wrapper>(value);
   }
+  
+  /**
+   * Specialized version of `std::optional<Powertrain>`.
+   */
+  using std__optional_Powertrain_ = std::optional<Powertrain>;
+  inline std::optional<Powertrain> create_std__optional_Powertrain_(const Powertrain& value) {
+    return std::optional<Powertrain>(value);
+  }
 
 } // namespace margelo::nitro::image::bridge::swift
diff --git a/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.cpp b/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.cpp
index 15586ed8e..6061111f4 100644
--- a/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.cpp
+++ b/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.cpp
@@ -29,6 +29,7 @@ namespace margelo::nitro::image {
       prototype.registerHybridMethod("asyncTest", &HybridKotlinTestObjectSpec::asyncTest);
       prototype.registerHybridMethod("createMap", &HybridKotlinTestObjectSpec::createMap);
       prototype.registerHybridMethod("addOnPersonBornListener", &HybridKotlinTestObjectSpec::addOnPersonBornListener);
+      prototype.registerHybridMethod("something1", &HybridKotlinTestObjectSpec::something1);
     });
   }
 
diff --git a/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.hpp b/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.hpp
index da69e0fb8..3ce2d5879 100644
--- a/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.hpp
+++ b/packages/react-native-nitro-image/nitrogen/generated/shared/c++/HybridKotlinTestObjectSpec.hpp
@@ -21,6 +21,8 @@ namespace NitroModules { class ArrayBuffer; }
 namespace NitroModules { class AnyMap; }
 // Forward declaration of `Person` to properly resolve imports.
 namespace margelo::nitro::image { struct Person; }
+// Forward declaration of `Powertrain` to properly resolve imports.
+namespace margelo::nitro::image { enum class Powertrain; }
 
 #include <optional>
 #include <vector>
@@ -32,6 +34,7 @@ namespace margelo::nitro::image { struct Person; }
 #include <NitroModules/AnyMap.hpp>
 #include <functional>
 #include "Person.hpp"
+#include "Powertrain.hpp"
 
 namespace margelo::nitro::image {
 
@@ -75,6 +78,7 @@ namespace margelo::nitro::image {
       virtual std::future<void> asyncTest() = 0;
       virtual std::shared_ptr<AnyMap> createMap() = 0;
       virtual void addOnPersonBornListener(const std::function<void(const Person& /* p */)>& callback) = 0;
+      virtual void something1(std::optional<Powertrain> optional) = 0;
 
     protected:
       // Hybrid Setup
diff --git a/packages/react-native-nitro-image/src/specs/TestObject.nitro.ts b/packages/react-native-nitro-image/src/specs/TestObject.nitro.ts
index 6a031eaa2..2c590185f 100644
--- a/packages/react-native-nitro-image/src/specs/TestObject.nitro.ts
+++ b/packages/react-native-nitro-image/src/specs/TestObject.nitro.ts
@@ -167,5 +167,7 @@ export interface KotlinTestObject extends HybridObject<{ android: 'kotlin' }> {
 
   addOnPersonBornListener(callback: (p: Person) => void): void
 
+  something1(optional?: Powertrain): void
+
   someRecord: Record<string, string>
 }