diff --git a/app/api/util.ts b/app/api/util.ts
index 132fac4aa8..35e3956060 100644
--- a/app/api/util.ts
+++ b/app/api/util.ts
@@ -22,11 +22,14 @@ import type {
   VpcFirewallRuleUpdate,
 } from './__generated__/Api'
 
-// API limits encoded in https://github.com/oxidecomputer/omicron/blob/aec3cd8d/nexus/src/app/mod.rs
+// API limits encoded in https://github.com/oxidecomputer/omicron/blob/44e65c3/nexus/src/app/mod.rs#L130-L161
 
 export const MAX_NICS_PER_INSTANCE = 8
 
-export const INSTANCE_MAX_CPU = 64
+// Limit is 254 on the backend but we haven't shipped any hardware that supports
+// that, so let's do 128 for now
+export const INSTANCE_MAX_CPU = 128
+
 export const INSTANCE_MIN_RAM_GiB = 1
 export const INSTANCE_MAX_RAM_GiB = 1536
 
diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index 45eac4465e..c4a9e67304 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -638,7 +638,7 @@ test('Validate CPU and RAM', async ({ page }) => {
 
   const submitButton = page.getByRole('button', { name: 'Create instance' })
 
-  const cpuMsg = page.getByText('Can be at most 64').first()
+  const cpuMsg = page.getByText('Can be at most 128').first()
   const memMsg = page.getByText('Can be at most 1536 GiB').first()
 
   await expect(cpuMsg).toBeHidden()