diff --git a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs
index a522ccb8c..4a8cdcb7e 100644
--- a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs
+++ b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs
@@ -2,26 +2,45 @@ using System.Dynamic;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using Elsa.Expressions.Contracts;
+using Elsa.Expressions.Services;
 
 namespace Elsa.Workflows.Serialization.Converters;
 
 /// <summary>
 /// A JSON converter factory that creates <see cref="PolymorphicObjectConverter"/> instances.
 /// </summary>
-public class PolymorphicObjectConverterFactory(IWellKnownTypeRegistry wellKnownTypeRegistry) : JsonConverterFactory
+public class PolymorphicObjectConverterFactory : JsonConverterFactory
 {
+    private readonly IWellKnownTypeRegistry _wellKnownTypeRegistry;
+
+    /// <summary>
+    /// A JSON converter factory that creates <see cref="PolymorphicObjectConverter"/> instances.
+    /// </summary>
+    public PolymorphicObjectConverterFactory(IWellKnownTypeRegistry wellKnownTypeRegistry)
+    {
+        _wellKnownTypeRegistry = wellKnownTypeRegistry;
+    }
+
+    /// <summary>
+    /// Default constructor for use with attributes.
+    /// </summary>
+    public PolymorphicObjectConverterFactory()
+    {
+        _wellKnownTypeRegistry = WellKnownTypeRegistry.CreateDefault();
+    }
+
     /// <inheritdoc />
     public override bool CanConvert(Type typeToConvert)
     {
         if (typeToConvert.IsClass
                && typeToConvert == typeof(object)
                || typeToConvert == typeof(ExpandoObject)
-               || typeToConvert == typeof(Dictionary<string, object>))
-            return true;
-
-        if (typeToConvert.IsInterface
-               && typeToConvert == typeof(IDictionary<string, object>))
-            return true;
+               || typeToConvert == typeof(Dictionary<string, object>))
+            return true;
+
+        if (typeToConvert.IsInterface
+               && typeToConvert == typeof(IDictionary<string, object>))
+            return true;
 
         return false;
     }
@@ -30,8 +49,8 @@ public class PolymorphicObjectConverterFactory(IWellKnownTypeRegistry wellKnownT
     public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options)
     {
         if (typeof(IDictionary<string, object>).IsAssignableFrom(typeToConvert))
-            return new PolymorphicDictionaryConverter(options, wellKnownTypeRegistry);
+            return new PolymorphicDictionaryConverter(options, _wellKnownTypeRegistry);
 
-        return new PolymorphicObjectConverter(wellKnownTypeRegistry);
+        return new PolymorphicObjectConverter(_wellKnownTypeRegistry);
     }
 }
\ No newline at end of file