diff --git a/.changeset/eighty-ducks-beam.md b/.changeset/eighty-ducks-beam.md
new file mode 100644
index 0000000000000000000000000000000000000000..dd960be1e2acef92a2ea925b88fa3d33482c5899
--- /dev/null
+++ b/.changeset/eighty-ducks-beam.md
@@ -0,0 +1,5 @@
+---
+"llamaindex": patch
+---
+
+fix: prefix messages always true
diff --git a/packages/core/src/agent/openai/base.ts b/packages/core/src/agent/openai/base.ts
index ff29ed31ed867422e20c470c2bd8182539c58771..3374c2a04832ea1bf2c3f65c2f9431a1fbaf26c7 100644
--- a/packages/core/src/agent/openai/base.ts
+++ b/packages/core/src/agent/openai/base.ts
@@ -37,8 +37,6 @@ export class OpenAIAgent extends AgentRunner {
     toolRetriever,
     systemPrompt,
   }: OpenAIAgentParams) {
-    prefixMessages = prefixMessages || [];
-
     llm = llm ?? new OpenAI({ model: "gpt-3.5-turbo-0613" });
 
     if (systemPrompt) {