diff --git a/src/app/api/purchase-orders/ingest/route.ts b/src/app/api/purchase-orders/ingest/route.ts
index 48d2286..db7e5b6 100644
--- a/src/app/api/purchase-orders/ingest/route.ts
+++ b/src/app/api/purchase-orders/ingest/route.ts
@@ -55,7 +55,7 @@ export async function POST(request: Request) {
   // 5. Idempotency: check for existing po_number
   try {
     const existing = await pb.collection("purchase_orders").getFullList({
-      filter: `purchase_order_number = "${payload.po_number.replace(/"/g, '\\"')}"`,
+      filter: `purchase_order_number = "${payload.po_number.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`,
     });
     if (existing.length > 0) {
       return NextResponse.json(