diff --git a/src/livekit/SileroVADGate.ts b/src/livekit/SileroVADGate.ts
index 86814bcf..2fd7cae9 100644
--- a/src/livekit/SileroVADGate.ts
+++ b/src/livekit/SileroVADGate.ts
@@ -6,6 +6,8 @@ Please see LICENSE in the repository root for full details.
 */
 
 import { MicVAD, getDefaultRealTimeVADOptions } from "@ricky0123/vad-web";
+// ort is not re-exported from the index, import from submodule
+import { ort } from "@ricky0123/vad-web/dist/real-time-vad";
 import { logger } from "matrix-js-sdk/lib/logger";
 
 const log = logger.getChild("[SileroVADGate]");
@@ -52,6 +54,10 @@ export class SileroVADGate {
 
     log.info("initialising MicVAD, baseAssetPath:", VAD_BASE_PATH);
 
+    // Avoid requiring SharedArrayBuffer (COOP/COEP headers) by running
+    // single-threaded. Performance is sufficient for 16kHz speech frames.
+    ort.env.wasm.numThreads = 1;
+
     this.vad = await MicVAD.new({
       ...getDefaultRealTimeVADOptions("legacy"),
       audioContext,
diff --git a/vite.config.ts b/vite.config.ts
index 792f5327..19e4a04b 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -50,6 +50,10 @@ export default ({
           src: "node_modules/onnxruntime-web/dist/*.wasm",
           dest: "vad",
         },
+        {
+          src: "node_modules/onnxruntime-web/dist/ort-wasm-simd-threaded.mjs",
+          dest: "vad",
+        },
       ],
     }),
     react(),
@@ -118,6 +122,11 @@ export default ({
         key: fs.readFileSync("./backend/dev_tls_m.localhost.key"),
         cert: fs.readFileSync("./backend/dev_tls_m.localhost.crt"),
       },
+      // Required for SharedArrayBuffer (used by onnxruntime-web threaded WASM)
+      headers: {
+        "Cross-Origin-Opener-Policy": "same-origin",
+        "Cross-Origin-Embedder-Policy": "require-corp",
+      },
     },
     worker: {
       format: "es",