diff --git a/core/llm/autodetect.ts b/core/llm/autodetect.ts
index 2ccc325cfb..8f5c7e8be1 100644
--- a/core/llm/autodetect.ts
+++ b/core/llm/autodetect.ts
@@ -142,7 +142,8 @@ function modelSupportsReasoning(
   if (!model) {
     return false;
   }
-  if ("anthropic" === model.underlyingProviderName) {
+  // do not turn reasoning on by default for claude 3 models
+  if (model.model.includes("claude") && !model.model.includes("-3-")) {
     return true;
   }
   if (model.model.includes("deepseek-r")) {