diff --git a/crates/esploda/src/bitcoind/tx.rs b/crates/esploda/src/bitcoind/tx.rs
index ee889a2..9f126e0 100644
--- a/crates/esploda/src/bitcoind/tx.rs
+++ b/crates/esploda/src/bitcoind/tx.rs
@@ -200,7 +200,9 @@ impl Transaction {
     ///
     /// # Panics
     ///
-    /// Asserts that `previous_outputs` and `self.inputs` have the same number of non-coinbase TXOs.
+    /// - Asserts that the computed `fee` is not negative.
+    /// - Asserts that `previous_outputs` and `self.inputs` have the same number of non-coinbase
+    ///   TXOs.
     ///
     /// [`esplora::Transaction`]: crate::esplora::Transaction
     pub fn into_esplora(
@@ -208,7 +210,12 @@ impl Transaction {
         block_height: u32,
         previous_outputs: Vec<TxOut>,
     ) -> crate::esplora::Transaction {
-        let fee = previous_outputs.iter().map(|txo| txo.value).sum();
+        let prev_outputs: Decimal = previous_outputs.iter().map(|txo| txo.value).sum();
+        let outputs: Decimal = self.outputs.iter().map(|txo| txo.value).sum();
+
+        let fee = prev_outputs - outputs;
+        assert!(!fee.is_sign_negative(), "Fee must never be negative");
+
         let mut previous_outputs = previous_outputs.into_iter();
         let inputs = self
             .inputs