diff --git a/src/consensus/tx_verify.cpp b/src/consensus/tx_verify.cpp
index 00022a33dd3..ec612a55e6f 100644
--- a/src/consensus/tx_verify.cpp
+++ b/src/consensus/tx_verify.cpp
@@ -197,6 +197,11 @@ bool Consensus::CheckTxInputs(const CTransaction& tx, TxValidationState& state,
     // Tally transaction fees
     const CAmount txfee_aux = nValueIn - value_out;
     if (!MoneyRange(txfee_aux)) {
+        // Unreachable, given the following preconditions:
+        // * `value_out` comes from `tx.GetValueOut()`, which throws unless `MoneyRange(value_out)` and asserts `MoneyRange(nValueOut)` on return.
+        // * `MoneyRange(nValueIn)` was enforced in the input loop.
+        // * `nValueIn < value_out` was handled above, so `nValueIn >= value_out` here (and `txfee_aux >= 0`).
+        // Therefore `0 <= txfee_aux = nValueIn - value_out <= nValueIn <= MAX_MONEY`.
         return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-fee-outofrange");
     }