diff --git a/src/lib/llm.js b/src/lib/llm.js
index 9e69f59..0edea82 100644
--- a/src/lib/llm.js
+++ b/src/lib/llm.js
@@ -303,9 +303,12 @@ export async function callLLM(options) {
   const body = {
     model,
     max_tokens: maxTokens,
-    temperature,
     messages: messagesPayload,
   };
+  // Temperature is not supported for reasoning tier models
+  if (tier !== 'reasoning') {
+    body.temperature = temperature;
+  }
   if (system !== undefined) body.system = system;
   if (tools && tools.length) body.tools = tools;
   if (toolChoice) body.tool_choice = toolChoice;