diff --git a/bitspire.py b/bitspire.py
index fa5620b..ac0a4b3 100644
--- a/bitspire.py
+++ b/bitspire.py
@@ -159,7 +159,13 @@ def _parse_extra(
         # Without exchange rate we can't compute fiat. Use 1.0 as a stand-in
         # and let the operator correct via manual reconciliation.
         exchange_rate = 1.0
-    fiat_amount = round(gross_sats / exchange_rate, 2) if exchange_rate > 0 else 0.0
+    # `fiat_amount` is sourced directly from bitSpire's bill validator /
+    # dispenser ledger (lamassu-next@8318489). It's the cash that
+    # physically entered (cash-in) or exited (cash-out) the machine —
+    # canonical, not derived. We never recompute it from sats × rate
+    # downstream: the relationship is't load-bearing (commission lives
+    # in BTC today, but the cash side has its own ground truth).
+    fiat_amount = _coerce_float(extra.get("fiat_amount")) or 0.0
     fiat_code = _coerce_str(extra.get("currency")) or machine.fiat_code
     return CreateDcaSettlementData(
         machine_id=machine.id,