diff --git a/packages/fxa-settings/src/lib/channels/pairing-channel.test.ts b/packages/fxa-settings/src/lib/channels/pairing-channel.test.ts
index dcc0b5cdadf..37a63ab9a81 100644
--- a/packages/fxa-settings/src/lib/channels/pairing-channel.test.ts
+++ b/packages/fxa-settings/src/lib/channels/pairing-channel.test.ts
@@ -22,6 +22,7 @@ let mockChannel: {
   _channelId?: string;
   _channelKey?: Uint8Array;
   _connection?: unknown;
+  closed?: boolean;
 };
 
 jest.mock(
@@ -56,6 +57,7 @@ describe('PairingChannelClient', () => {
       // 'testkey1' — the same bytes VALID_KEY decodes to.
       _channelId: CHAN,
       _channelKey: new TextEncoder().encode('testkey1'),
+      closed: false,
     };
     jest.clearAllMocks();
     client = new PairingChannelClient();
@@ -186,6 +188,16 @@ describe('PairingChannelClient', () => {
       await expect(client.send('msg')).rejects.toThrow('Not connected');
     });
 
+    it('throws CONNECTION_CLOSED when the channel is torn down', async () => {
+      await client.open(SERVER, CHAN, VALID_KEY);
+      mockChannel.closed = true;
+
+      await expect(client.send('pair:supp:authorize')).rejects.toMatchObject({
+        errno: 1006,
+      });
+      expect(mockChannel.send).not.toHaveBeenCalled();
+    });
+
     it('throws for empty message', async () => {
       await client.open(SERVER, CHAN, VALID_KEY);
       await expect(client.send('')).rejects.toThrow('malformed message');
diff --git a/packages/fxa-settings/src/lib/channels/pairing-channel.ts b/packages/fxa-settings/src/lib/channels/pairing-channel.ts
index bc52bd7d167..e82066910c8 100644
--- a/packages/fxa-settings/src/lib/channels/pairing-channel.ts
+++ b/packages/fxa-settings/src/lib/channels/pairing-channel.ts
@@ -156,6 +156,8 @@ type PairingChannelSocket = {
    * socket goes away, and the package's `close()` dereferences it unguarded.
    */
   _connection?: unknown;
+  /** True once fxa-pairing-channel has torn the WebSocket down. */
+  readonly closed?: boolean;
 };
 
 export class PairingChannelClient extends EventTarget {
@@ -291,6 +293,10 @@ export class PairingChannelClient extends EventTarget {
       console.warn('No pairing channel!');
       throw new PairingChannelError('NOT_CONNECTED');
     }
+    if (this.channel.closed) {
+      console.warn('Pairing channel is closed!');
+      throw new PairingChannelError('CONNECTION_CLOSED');
+    }
     if (!message) {
       console.warn('No message!');
       throw new PairingChannelError('INVALID_OUTBOUND_MESSAGE');