diff --git a/src/open_prompt_extension.cpp b/src/open_prompt_extension.cpp
index 767df49..b4c8155 100644
--- a/src/open_prompt_extension.cpp
+++ b/src/open_prompt_extension.cpp
@@ -24,15 +24,18 @@ namespace duckdb {
     struct OpenPromptData: FunctionData {
         idx_t model_idx;
         idx_t json_schema_idx;
+        idx_t json_system_prompt_idx;
         unique_ptr<FunctionData> Copy() const {
             auto res = make_uniq<OpenPromptData>();
             res->model_idx = model_idx;
             res->json_schema_idx = json_schema_idx;
+            res->json_system_prompt_idx = json_system_prompt_idx;
             return res;
         };
         bool Equals(const FunctionData &other) const {
             return model_idx == other.Cast<OpenPromptData>().model_idx &&
-                json_schema_idx == other.Cast<OpenPromptData>().json_schema_idx;
+                json_schema_idx == other.Cast<OpenPromptData>().json_schema_idx &&
+                json_system_prompt_idx==other.Cast<OpenPromptData>().json_system_prompt_idx;
         };
         OpenPromptData() {
             model_idx = 0;
@@ -49,6 +52,8 @@ namespace duckdb {
                 res->model_idx = i;
             } else if (argument->alias == "json_schema") {
                 res->json_schema_idx = i;
+            } else if (argument->alias == "system_prompt") {
+                res->json_system_prompt_idx = i;
             }
         }
         return std::move(res);
@@ -182,6 +187,7 @@ static void OpenPromptRequestFunction(DataChunk &args, ExpressionState &state, V
             std::string api_token = GetConfigValue(context, "openprompt_api_token", "");
             std::string model_name = GetConfigValue(context, "openprompt_model_name", "qwen2.5:0.5b");
             std::string json_schema;
+            std::string system_prompt;
 
             if (info.model_idx != 0) {
                 model_name = args.data[info.model_idx].GetValue(0).ToString();
@@ -189,11 +195,14 @@ static void OpenPromptRequestFunction(DataChunk &args, ExpressionState &state, V
             if (info.json_schema_idx != 0) {
                 json_schema = args.data[info.json_schema_idx].GetValue(0).ToString();
             }
+            if (info.json_system_prompt_idx != 0) {
+                system_prompt = args.data[info.json_system_prompt_idx].GetValue(0).ToString();
+            }
 
-            unique_ptr<duckdb_yyjson::yyjson_mut_doc,
-                void (*)(duckdb_yyjson::yyjson_mut_doc*)> doc(
-                    new duckdb_yyjson::yyjson_mut_doc(), &duckdb_yyjson::yyjson_mut_doc_free);
+            unique_ptr<duckdb_yyjson::yyjson_mut_doc, void (*)(duckdb_yyjson::yyjson_mut_doc*)> doc(
+                    duckdb_yyjson::yyjson_mut_doc_new(nullptr), &duckdb_yyjson::yyjson_mut_doc_free);
             auto obj = duckdb_yyjson::yyjson_mut_obj(doc.get());
+            duckdb_yyjson::yyjson_mut_doc_set_root(doc.get(), obj);
             duckdb_yyjson::yyjson_mut_obj_add(obj,
                 duckdb_yyjson::yyjson_mut_str(doc.get(), "model"),
                 duckdb_yyjson::yyjson_mut_str(doc.get(), model_name.c_str())
@@ -213,23 +222,30 @@ static void OpenPromptRequestFunction(DataChunk &args, ExpressionState &state, V
             }
             auto messages = duckdb_yyjson::yyjson_mut_arr(doc.get());
             string str_messages[2][2] = {
-                {"system", "You are a helpful assistant."},
+                {"system", system_prompt},
                 {"user", user_prompt.GetString()}
             };
             for (auto message : str_messages) {
                 if (message[1].empty()) {
                     continue;
                 }
-                auto yymessage = duckdb_yyjson::yyjson_mut_obj(doc.get());
-
+                auto yymessage = duckdb_yyjson::yyjson_mut_arr_add_obj(doc.get(),messages);
+                duckdb_yyjson::yyjson_mut_obj_add(yymessage,
+                    duckdb_yyjson::yyjson_mut_str(doc.get(), "role"),
+                    duckdb_yyjson::yyjson_mut_str(doc.get(), message[0].c_str()));
+                duckdb_yyjson::yyjson_mut_obj_add(yymessage,
+                    duckdb_yyjson::yyjson_mut_str(doc.get(), "content"),
+                    duckdb_yyjson::yyjson_mut_str(doc.get(), message[1].c_str()));
             }
             duckdb_yyjson::yyjson_mut_obj_add(obj, duckdb_yyjson::yyjson_mut_str(doc.get(), "messages"),
-                )
-            request_body += "\"messages\":[";
-            request_body += "{\"role\":\"system\",\"content\":\"You are a helpful assistant.\"},";
-            request_body += "{\"role\":\"user\",\"content\":\"" + user_prompt.GetString() + "\"}";
-            request_body += "]}";
-
+                messages);
+            duckdb_yyjson::yyjson_write_err err;
+            auto request_body = duckdb_yyjson::yyjson_mut_write_opts(doc.get(), 0, nullptr, nullptr, &err);
+            if (request_body == nullptr) {
+                throw std::runtime_error(err.msg);
+            }
+            string str_request_body(request_body);
+            free(request_body);
 
             try {
                 auto client_and_path = SetupHttpClient(api_url);
@@ -242,7 +258,7 @@ static void OpenPromptRequestFunction(DataChunk &args, ExpressionState &state, V
                     headers.emplace("Authorization", "Bearer " + api_token);
                 }
 
-                auto res = client.Post(path.c_str(), headers, request_body, "application/json");
+                auto res = client.Post(path.c_str(), headers, str_request_body, "application/json");
                 
                 if (!res) {
                     HandleHttpError(res, "POST");
@@ -314,10 +330,14 @@ static void LoadInternal(DatabaseInstance &instance) {
     open_prompt.AddFunction(ScalarFunction(
         {LogicalType::VARCHAR, LogicalType::VARCHAR}, LogicalType::VARCHAR, OpenPromptRequestFunction,
         OpenPromptBind));
-        open_prompt.AddFunction(ScalarFunction(
+    open_prompt.AddFunction(ScalarFunction(
         {LogicalType::VARCHAR, LogicalType::VARCHAR, LogicalType::VARCHAR},
         LogicalType::VARCHAR, OpenPromptRequestFunction,
         OpenPromptBind));
+    open_prompt.AddFunction(ScalarFunction(
+        {LogicalType::VARCHAR, LogicalType::VARCHAR, LogicalType::VARCHAR, LogicalType::VARCHAR},
+        LogicalType::VARCHAR, OpenPromptRequestFunction,
+        OpenPromptBind));
     
     ExtensionUtil::RegisterFunction(instance, open_prompt);