diff --git a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs
index 72d2c3183..0cc00867a 100644
--- a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs
+++ b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs
@@ -158,7 +158,7 @@ public class PolymorphicObjectConverter : JsonConverter<object>
         var newOptions = new JsonSerializerOptions(options);
         var type = value.GetType();
 
-        if (type.IsPrimitive || value is string or DateTimeOffset or DateTime or DateOnly or TimeOnly or JsonElement or Guid or TimeSpan or Uri or Version or Enum)
+        if (type.IsPrimitive || value is string or decimal or DateTimeOffset or DateTime or DateOnly or TimeOnly or JsonElement or Guid or TimeSpan or Uri or Version or Enum)
         {
             // Remove the converter so that we don't end up in an infinite loop.
             newOptions.Converters.RemoveWhere(x => x is PolymorphicObjectConverterFactory);