diff --git a/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs b/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs
index fc829f41c..2af9c2334 100644
--- a/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs
+++ b/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs
@@ -20,13 +20,13 @@ public class ArgumentJsonConverter : JsonConverter<ArgumentDefinition>
     {
         _wellKnownTypeRegistry = wellKnownTypeRegistry;
     }
-    
+
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, ArgumentDefinition value, JsonSerializerOptions options)
     {
         var newOptions = new JsonSerializerOptions(options);
         newOptions.Converters.RemoveWhere(x => x is ArgumentJsonConverterFactory);
-        
+
         var jsonObject = (JsonObject)JsonSerializer.SerializeToNode(value, value.GetType(), newOptions)!;
         var typeName = value.Type;
         var typeAlias = _wellKnownTypeRegistry.TryGetAlias(typeName, out var alias) ? alias : null;
@@ -34,11 +34,12 @@ public class ArgumentJsonConverter : JsonConverter<ArgumentDefinition>
         var isCollection = typeName.IsCollectionType();
         var elementTypeName = isArray ? typeName.GetElementType() : isCollection ? typeName.GenericTypeArguments[0] : typeName;
         var elementTypeAlias = _wellKnownTypeRegistry.GetAliasOrDefault(elementTypeName);
-        var finalTypeAlias = isArray || isCollection ? elementTypeAlias : typeAlias;
-        
-        if(isArray) jsonObject["isArray"] = isArray;
-        if(isCollection) jsonObject["isCollection"] = isCollection;
-        
+        var isAliasedArray = (isArray || isCollection) && typeAlias != null;
+        var finalTypeAlias = isArray || isCollection ? typeAlias ?? elementTypeAlias : elementTypeAlias;
+
+        if (isArray && !isAliasedArray) jsonObject["isArray"] = isArray;
+        if (isCollection) jsonObject["isCollection"] = isCollection;
+
         jsonObject["type"] = finalTypeAlias;
         JsonSerializer.Serialize(writer, jsonObject, newOptions);
     }