diff --git a/server.js b/server.js
index 9f69c83..8e1b4f9 100644
--- a/server.js
+++ b/server.js
@@ -234,7 +234,10 @@ function runCodexEdit(jobDir, inputName, prompt) {
   }
 
   if (process.env.CODEX_REASONING_EFFORT) {
-    args.push("--reasoning-effort", process.env.CODEX_REASONING_EFFORT);
+    args.push(
+      "-c",
+      `model_reasoning_effort=${process.env.CODEX_REASONING_EFFORT}`
+    );
   }
 
   args.push("-i", inputName, "-o", "last_message.txt", "-");