diff --git a/packages/openai-adapters/src/apis/OpenAI.ts b/packages/openai-adapters/src/apis/OpenAI.ts
index d0f8d30ca3a..3ff2a33cc96 100644
--- a/packages/openai-adapters/src/apis/OpenAI.ts
+++ b/packages/openai-adapters/src/apis/OpenAI.ts
@@ -44,6 +44,10 @@ export class OpenAIApi implements BaseLlmApi {
       // Necessary because `new OpenAI()` will throw an error if there is no API Key
       apiKey: config.apiKey ?? "",
       baseURL: this.apiBase,
+      defaultHeaders: {
+        "openai-organization": undefined,
+        "openai-project": undefined,
+      },
       fetch: customFetch(config.requestOptions),
       timeout: config?.requestOptions?.timeout || undefined,
     });
diff --git a/packages/openai-adapters/src/test/main.test.ts b/packages/openai-adapters/src/test/main.test.ts
index 8a10c8b727f..300d1101e6c 100644
--- a/packages/openai-adapters/src/test/main.test.ts
+++ b/packages/openai-adapters/src/test/main.test.ts
@@ -235,6 +235,19 @@ describe("Configuration", () => {
     );
   });
 
+  it("should disable optional OpenAI org/project headers with lowercase keys", () => {
+    const openai = constructLlmApi({
+      provider: "openai",
+      apiKey: "sk-xxx",
+      apiBase: "https://openrouter.ai/api/v1/",
+    }) as OpenAIApi;
+
+    expect((openai.openai as any)._options.defaultHeaders).toMatchObject({
+      "openai-organization": undefined,
+      "openai-project": undefined,
+    });
+  });
+
   it("should configure Inception OpenAI client with correct apiBase and apiKey", () => {
     const inception = constructLlmApi({
       provider: "inception",