diff --git a/examples/server/utils.hpp b/examples/server/utils.hpp
index a1865e73d..71a035bf4 100644
--- a/examples/server/utils.hpp
+++ b/examples/server/utils.hpp
@@ -370,8 +370,10 @@ static json oaicompat_completion_params_parse(
     } else {
         llama_params["stop"] = json_value(body, "stop", json::array());
     }
-    // Ensure there is ChatML-specific end sequence among stop words
-    llama_params["stop"].push_back("<|im_end|>");
+    // Some chat templates don't use EOS token to stop generation
+    // We must add their end sequences among stop words
+    llama_params["stop"].push_back("<|im_end|>"); // chatml
+    llama_params["stop"].push_back("<end_of_turn>"); // gemma
 
     // Handle "response_format" field
     if (body.contains("response_format")) {
@@ -379,23 +381,28 @@ static json oaicompat_completion_params_parse(
         std::string response_type = json_value(response_format, "type", std::string());
         if (response_type == "json_object") {
             llama_params["json_schema"] = json_value(response_format, "schema", json::object());
-        } else if (!response_type.empty()) {
-            throw std::runtime_error("response_format type not supported: " + response_type);
+        } else if (!response_type.empty() && response_type != "text") {
+            throw std::runtime_error("response_format type must be one of \"text\" or \"json_object\", but got: " + response_type);
         }
     }
 
     // Handle "n" field
     int n_choices = json_value(body, "n", 1);
     if (n_choices != 1) {
-        throw std::runtime_error("Only one completion choice is supported");
+        throw std::runtime_error("Only one completion choice is allowed");
+    }
+
+    // Handle "logprobs" field
+    if (body.contains("logprobs")) {
+        llama_params["n_probs"] = json_value(body, "top_logprobs", 20);
+    } else if (body.contains("top_logprobs")) {
+        throw std::runtime_error("top_logprobs requires logprobs to be set to true");
     }
 
     // Params supported by OAI but unsupported by llama.cpp
-    static const std::vector<std::string> unsupported_params{
-        "logprobs", "top_logprobs", "tools", "tool_choice"
-    };
+    static const std::vector<std::string> unsupported_params { "tools", "tool_choice" };
     for (auto & param : unsupported_params) {
-        if (llama_params.contains(param)) {
+        if (body.contains(param)) {
             throw std::runtime_error("Unsupported param: " + param);
         }
     }
@@ -404,7 +411,7 @@ static json oaicompat_completion_params_parse(
     // This allows user to use llama.cpp-specific params like "mirostat", "tfs_z",... via OAI endpoint.
     // See "launch_slot_with_task()" for a complete list of params supported by llama.cpp
     for (const auto & item : body.items()) {
-        // Exception: if "n_predict" is present, we overwrite the value specified by "max_tokens"
+        // Exception: if "n_predict" is present, we overwrite the value specified earlier by "max_tokens"
         if (!llama_params.contains(item.key()) || item.key() == "n_predict") {
             llama_params[item.key()] = item.value();
         }