diff --git a/extensions/general/invoice-inbox/lib/extract-invoice-fields.ts b/extensions/general/invoice-inbox/lib/extract-invoice-fields.ts
index c33861b1..8ac91e3e 100644
--- a/extensions/general/invoice-inbox/lib/extract-invoice-fields.ts
+++ b/extensions/general/invoice-inbox/lib/extract-invoice-fields.ts
@@ -13,6 +13,18 @@ import type { InvoiceExtractionResult } from '@/types'
 import { normalizeOrgNumber } from '@/lib/company-lookup/normalize-org-number'
 import { validateOcrReference, validateBankgiroNumber } from '@/lib/bankgiro/luhn'
 
+// pdfjs-dist references DOMMatrix/ImageData/Path2D at module load. On
+// Vercel's Node runtime these globals don't exist; without stubs the
+// dynamic import throws "DOMMatrix is not defined" before getDocument()
+// runs. We only call getTextContent (no rendering), so empty-class stubs
+// are enough — pdfjs never invokes any methods on them.
+{
+  const g = globalThis as unknown as { DOMMatrix?: unknown; ImageData?: unknown; Path2D?: unknown }
+  if (typeof g.DOMMatrix === 'undefined') g.DOMMatrix = class {}
+  if (typeof g.ImageData === 'undefined') g.ImageData = class {}
+  if (typeof g.Path2D === 'undefined') g.Path2D = class {}
+}
+
 // Below this we treat the document as image-only / unreadable and skip
 // regex extraction. pdfjs-dist returns near-zero text for scanned PDFs.
 const MIN_TEXT_CHARS_FOR_EXTRACTION = 10
diff --git a/next.config.ts b/next.config.ts
index 723d11bb..2b4b4b2e 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -20,6 +20,11 @@ const cspDirectives = [
 
 const nextConfig: NextConfig = {
   output: 'standalone',
+  // Keep pdfjs-dist out of the bundle. The legacy build references
+  // @napi-rs/canvas at module load and breaks Vercel's bundling step.
+  // Text extraction works in pure Node once DOM globals are stubbed at
+  // the call site (see extensions/general/invoice-inbox/lib/extract-invoice-fields.ts).
+  serverExternalPackages: ['pdfjs-dist'],
   async redirects() {
     return [
       {