diff --git a/package.json b/package.json
index 14e57a3..0f99326 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "assemblyai",
-  "version": "4.34.4",
+  "version": "4.34.5",
   "description": "The AssemblyAI JavaScript SDK provides an easy-to-use interface for interacting with the AssemblyAI API, which supports async and real-time transcription, as well as the latest LeMUR models.",
   "engines": {
     "node": ">=18"
diff --git a/src/services/streaming/service.ts b/src/services/streaming/service.ts
index b1249dd..1bb5537 100644
--- a/src/services/streaming/service.ts
+++ b/src/services/streaming/service.ts
@@ -283,6 +283,10 @@ export class StreamingTranscriber {
       searchParams.set("speech_model", this.params.speechModel.toString());
     }
 
+    if (this.params.languageCode !== undefined) {
+      searchParams.set("language_code", this.params.languageCode);
+    }
+
     if (this.params.languageDetection !== undefined) {
       searchParams.set(
         "language_detection",
diff --git a/src/types/streaming/index.ts b/src/types/streaming/index.ts
index 91e4516..e24557b 100644
--- a/src/types/streaming/index.ts
+++ b/src/types/streaming/index.ts
@@ -93,6 +93,7 @@ export type StreamingTranscriberParams = {
   prompt?: string;
   agentContext?: string;
   speechModel?: StreamingSpeechModel;
+  languageCode?: string;
   languageDetection?: boolean;
   domain?: StreamingDomain;
   inactivityTimeout?: number;
diff --git a/tests/unit/streaming.test.ts b/tests/unit/streaming.test.ts
index dacecea..4914453 100644
--- a/tests/unit/streaming.test.ts
+++ b/tests/unit/streaming.test.ts
@@ -303,6 +303,24 @@ describe("streaming", () => {
     await connect(rt, server);
   });
 
+  it("should include language_code in connection URL", async () => {
+    await cleanup();
+    WS.clean();
+
+    const wsUrl = `${websocketBaseUrl}?token=123&sample_rate=16000&speech_model=u3-rt-pro&language_code=es`;
+    server = new WS(wsUrl);
+    rt = new StreamingTranscriber({
+      websocketBaseUrl,
+      token: "123",
+      sampleRate: 16_000,
+      speechModel: "u3-rt-pro",
+      languageCode: "es",
+    });
+    onOpen = jest.fn();
+    rt.on("open", onOpen);
+    await connect(rt, server);
+  });
+
   it("should include whisper-rt speech model in connection URL", async () => {
     await cleanup();
     WS.clean();