diff --git a/examples/server/utils.hpp b/examples/server/utils.hpp
index 89c3038ef..f2af3dac7 100644
--- a/examples/server/utils.hpp
+++ b/examples/server/utils.hpp
@@ -49,34 +49,6 @@ extern bool server_log_json;
 #define LOG_WARNING(MSG, ...) server_log("WARN", __func__, __LINE__, MSG, __VA_ARGS__)
 #define LOG_INFO(   MSG, ...) server_log("INFO", __func__, __LINE__, MSG, __VA_ARGS__)
 
-// GRAMMAR_JSON is used by OAI "response_format" field
-static const std::string GRAMMAR_JSON = R"(root   ::= object
-value  ::= object | array | string | number | ("true" | "false" | "null") ws
-
-object ::=
-  "{" ws (
-            string ":" ws value
-    ("," ws string ":" ws value)*
-  )? "}" ws
-
-array  ::=
-  "[" ws (
-            value
-    ("," ws value)*
-  )? "]" ws
-
-string ::=
-  "\"" (
-    [^"\\\x7F\x00-\x1F] |
-    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F]) # escapes
-  )* "\"" ws
-
-number ::= ("-"? ([0-9] | [1-9] [0-9]*)) ("." [0-9]+)? ([eE] [-+]? [0-9]+)? ws
-
-# Optional space: by convention, applied in this grammar after literal chars when allowed
-ws ::= ([ \t\n] ws)?
-)";
-
 template <typename T>
 static T json_value(const json &body, const std::string &key, const T &default_value) {
     // Fallback null to default value
@@ -404,10 +376,9 @@ static json oaicompat_completion_params_parse(
     // Handle "response_format" field
     if (body.contains("response_format")) {
         json response_format      = json_value(body, "response_format", json::object());
-        std::string response_type = json_value(response_format, "type", std::string());
+        std::string response_type = json_value(response_format, "type", std::string("unknown"));
         if (response_type == "json_object") {
-            // "json_object" guarantees the message the model generates is valid JSON.
-            llama_params["grammar"] = GRAMMAR_JSON;
+            llama_params["json_schema"] = json_value(response_format, "schema", json::object());
         } else {
             throw std::runtime_error("response_format type not supported: " + response_type);
         }