diff --git a/src/lib.rs b/src/lib.rs
index 0a9445f1..e3dac71b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -55,7 +55,18 @@ pub struct WeightedUtxo {
 
 impl WeightedUtxo {
     fn effective_value(&self, fee_rate: FeeRate) -> Option<SignedAmount> {
-        effective_value(fee_rate, self.satisfaction_weight, self.utxo.value)
+        let signed_input_fee = self.calculate_fee(fee_rate)?.to_signed().ok()?;
+        self.utxo.value.to_signed().ok()?.checked_sub(signed_input_fee)
+    }
+
+    fn calculate_fee(&self, fee_rate: FeeRate) -> Option<Amount> {
+        // TODO TxIn::BASE_WEIGHT
+        let weight = self.satisfaction_weight.checked_add(Weight::ZERO)?;
+        fee_rate.checked_mul_by_weight(weight)
+    }
+
+    fn is_wasteful(&self, fee_rate: FeeRate, long_term_fee_rate: FeeRate) -> bool {
+        self.calculate_fee(fee_rate) > self.calculate_fee(long_term_fee_rate)
     }
 }