diff --git a/vendor/web-audio-api-1.7.0/src/context/online.rs b/vendor/web-audio-api-1.7.0/src/context/online.rs
index a461db904b..7d9117282e 100644
--- a/vendor/web-audio-api-1.7.0/src/context/online.rs
+++ b/vendor/web-audio-api-1.7.0/src/context/online.rs
@@ -619,7 +619,11 @@ impl AudioContext {
         // Stop AudioRenderCapacity before closing so no capacity events are queued during shutdown.
         self.render_capacity.stop();
 
-        if self.state() == AudioContextState::Running {
+        // Startup can still be queued while the initial state is Suspended.
+        // Serialize Close after it before shutting down the backend.
+        if self.startup_pending.load(Ordering::Acquire)
+            || self.state() == AudioContextState::Running
+        {
             // First, stop rendering via a control message
             let (sender, receiver) = oneshot::channel();
             let notify = OneshotNotify::Async(sender);
@@ -759,8 +763,11 @@ impl AudioContext {
         // Stop AudioRenderCapacity before closing so no capacity events are queued during shutdown.
         self.render_capacity.stop();
 
-        // First, stop rendering via a control message
-        if self.state() == AudioContextState::Running {
+        // Startup must settle before the backend stops, even if the initial
+        // Suspended state has not yet transitioned to Running.
+        if self.startup_pending.load(Ordering::Acquire)
+            || self.state() == AudioContextState::Running
+        {
             let (sender, receiver) = crossbeam_channel::bounded(0);
             let notify = OneshotNotify::Sync(sender);
             self.base.send_control_msg(ControlMessage::Close { notify });
@@ -918,6 +925,38 @@ mod tests {
 
     fn require_send_sync<T: Send + Sync>(_: T) {}
 
+    #[test]
+    fn test_close_sync_during_startup_is_terminal() {
+        let context = AudioContext::new(AudioContextOptions {
+            sink_id: "none".into(),
+            ..AudioContextOptions::default()
+        });
+        context.close_sync();
+        assert!(
+            !context.startup_pending.load(Ordering::Acquire),
+            "close must settle the queued Startup before stopping its backend"
+        );
+        assert_eq!(context.state(), AudioContextState::Closed);
+        context.close_sync();
+        assert_eq!(context.state(), AudioContextState::Closed);
+    }
+
+    #[test]
+    fn test_close_during_startup_is_terminal() {
+        let context = AudioContext::new(AudioContextOptions {
+            sink_id: "none".into(),
+            ..AudioContextOptions::default()
+        });
+        executor::block_on(context.close());
+        assert!(
+            !context.startup_pending.load(Ordering::Acquire),
+            "close must settle the queued Startup before stopping its backend"
+        );
+        assert_eq!(context.state(), AudioContextState::Closed);
+        context.close_sync();
+        assert_eq!(context.state(), AudioContextState::Closed);
+    }
+
     #[test]
     fn test_all_futures_thread_safe() {
         let options = AudioContextOptions {
diff --git a/vendor/web-audio-api-1.7.0/src/render/thread.rs b/vendor/web-audio-api-1.7.0/src/render/thread.rs
index c684954968..20353812d3 100644
--- a/vendor/web-audio-api-1.7.0/src/render/thread.rs
+++ b/vendor/web-audio-api-1.7.0/src/render/thread.rs
@@ -191,10 +191,11 @@ impl RenderThread {
             Startup { graph } => {
                 debug_assert!(self.graph.is_none());
                 self.graph = Some(graph);
+                self.set_state(AudioContextState::Running);
                 if let Some(startup_pending) = self.startup_pending.as_ref() {
+                    // Observing startup completion must also observe Running.
                     startup_pending.store(false, Ordering::Release);
                 }
-                self.set_state(AudioContextState::Running);
             }
             NodeMessage { id, mut msg } => {
                 self.graph.as_mut().unwrap().route_message(id, msg.as_mut());