diff --git a/src/__tests__/messageCreate.test.ts b/src/__tests__/messageCreate.test.ts
index 0651014..c36f500 100644
--- a/src/__tests__/messageCreate.test.ts
+++ b/src/__tests__/messageCreate.test.ts
@@ -58,6 +58,19 @@ test('handleMessageCreate ignores bot messages', async () => {
   assert.equal(enqueued, 0);
 });
 
+test('handleMessageCreate ignores system messages (e.g. thread rename)', async () => {
+  let enqueued = 0;
+  const handler = createMessageCreateHandler(
+    createDeps(() => {
+      enqueued += 1;
+    }),
+  );
+
+  // A thread rename arrives as a system message whose content is the new name.
+  await handler(makeMessage({ system: true, content: 'renamed-thread' }) as any);
+  assert.equal(enqueued, 0);
+});
+
 test('handleMessageCreate ignores DMs', async () => {
   let enqueued = 0;
   const handler = createMessageCreateHandler(
diff --git a/src/providers/discord/messageCreate.ts b/src/providers/discord/messageCreate.ts
index 015aeab..30af786 100644
--- a/src/providers/discord/messageCreate.ts
+++ b/src/providers/discord/messageCreate.ts
@@ -49,6 +49,7 @@ function toIncoming(message: Message, attachmentSource?: IncomingAttachment[]):
 export function createMessageCreateHandler(deps: MessageCreateDeps) {
   return async function handleMessageCreate(message: Message): Promise<void> {
     if (message.author.bot) return;
+    if (message.system) return;
     if (!message.guild) return;
 
     if (!message.content.trim() && message.attachments.size === 0) return;