diff --git a/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/TxOut.hs b/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/TxOut.hs
index 67d61cf7406..82ec595ff6d 100644
--- a/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/TxOut.hs
+++ b/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/TxOut.hs
@@ -294,7 +294,8 @@ pattern AlonzoTxOut addr vl dh <-
         Just (Refl, dataHash32) <- encodeDataHash32 dh =
           TxOut_AddrHash28_AdaOnly_DataHash32 stakeCred addr28Extra adaCompact dataHash32
     AlonzoTxOut addr vl mdh =
-      let v = fromMaybe (error "Illegal value in txout") $ toCompact vl
+      let x = toCompact vl
+          v = fromMaybe (error "Illegal value in txout") $ x
           a = compactAddr addr
        in case mdh of
             SNothing -> TxOutCompact' a v