diff --git a/.changeset/thin-crews-shout.md b/.changeset/thin-crews-shout.md
new file mode 100644
index 0000000..98ebfe4
--- /dev/null
+++ b/.changeset/thin-crews-shout.md
@@ -0,0 +1,5 @@
+---
+"@dormice/sdk": patch
+---
+
+Fix `updateApiKey` so a patch object can no longer override the target id. Before this, `{ id, ...patch }` let an `id` field inside `patch` win over the id you pass as the first argument, so the request could edit the wrong key.
diff --git a/packages/sdk/src/client.test.ts b/packages/sdk/src/client.test.ts
index 33f5674..660a22b 100644
--- a/packages/sdk/src/client.test.ts
+++ b/packages/sdk/src/client.test.ts
@@ -421,6 +421,30 @@ describe('API keys over real HTTP', () => {
     await client.revokeApiKey(apiKey.id);
   });
 
+  it('updateApiKey ignores an id smuggled inside the patch object', async () => {
+    const { apiKey: intended } = await client.createApiKey('sdk-target');
+    const { apiKey: victim } = await client.createApiKey('sdk-victim');
+
+    // A patch variable can carry an `id` field through structural typing
+    // (TypeScript excess-property checks only catch object literals, not
+    // variables). The wire request must still target the id passed as the
+    // method's own argument, not one hiding inside the patch.
+    const patch = { id: victim.id, disabled: true } as { disabled: boolean };
+    const result = await client.updateApiKey(intended.id, patch);
+
+    expect(result.apiKey.id).toBe(intended.id);
+    expect(result.apiKey.disabledAt).not.toBeNull();
+
+    const allKeys = await client.listApiKeys();
+    const refreshedIntended = allKeys.find((key) => key.id === intended.id);
+    const refreshedVictim = allKeys.find((key) => key.id === victim.id);
+    expect(refreshedIntended?.disabledAt).not.toBeNull();
+    expect(refreshedVictim?.disabledAt).toBeNull();
+
+    await client.revokeApiKey(intended.id);
+    await client.revokeApiKey(victim.id);
+  });
+
   it('a ledger key gets the honest 403 on the management verbs', async () => {
     const { apiKey, token } = await client.createApiKey('sdk-not-admin');
     const keyed = new Dormice({ endpoint, token });
diff --git a/packages/sdk/src/client.ts b/packages/sdk/src/client.ts
index b2011d0..ea611c6 100644
--- a/packages/sdk/src/client.ts
+++ b/packages/sdk/src/client.ts
@@ -589,7 +589,11 @@ export class Dormice {
     id: string,
     patch: { name?: string; expiresAt?: string | null; disabled?: boolean },
   ): Promise<UpdateApiKeyResponse> {
-    const data = await this.rpc('updateApiKey', { id, ...patch });
+    // Spread patch first so its fields can never clobber the id we were
+    // explicitly asked to target (a patch variable can carry an `id` of
+    // its own through structural typing, since excess-property checks
+    // only apply to object literals).
+    const data = await this.rpc('updateApiKey', { ...patch, id });
     return updateApiKeyResponseSchema.parse(data);
   }