diff --git a/src/Ledger/Conway/Conformance/Utxow.agda b/src/Ledger/Conway/Conformance/Utxow.agda
index 4563e966a..b571ee9d2 100644
--- a/src/Ledger/Conway/Conformance/Utxow.agda
+++ b/src/Ledger/Conway/Conformance/Utxow.agda
@@ -38,6 +38,7 @@ data _⊢_⇀⦇_,UTXOW⦈_ where
         refScriptHashes     = mapˢ hash (refScripts tx utxo)
         neededScriptHashes  = mapPartial (isScriptObj  ∘ proj₂) (credsNeeded utxo txb)
         neededVKeyHashes    = mapPartial (isKeyHashObj ∘ proj₂) (credsNeeded utxo txb)
+                              ∪ reqSignerHashes
         txdatsHashes        = mapˢ hash txdats
         inputsDataHashes    = mapPartial (λ txout → if txOutToP2Script utxo tx txout
                                                      then txOutToDataHash txout
diff --git a/src/Ledger/Conway/Specification/Utxow.lagda.md b/src/Ledger/Conway/Specification/Utxow.lagda.md
index 256108eee..8a022ed22 100644
--- a/src/Ledger/Conway/Specification/Utxow.lagda.md
+++ b/src/Ledger/Conway/Specification/Utxow.lagda.md
@@ -123,6 +123,7 @@ data _⊢_⇀⦇_,UTXOW⦈_ : UTxOEnv → UTxOState → Tx → UTxOState → Typ
          refScriptHashes     = mapˢ hash (refScripts tx utxo)
          neededScriptHashes  = mapPartial (isScriptObj  ∘ proj₂) (credsNeeded utxo txb)
          neededVKeyHashes    = mapPartial (isKeyHashObj ∘ proj₂) (credsNeeded utxo txb)
+                               ∪ reqSignerHashes
          txdatsHashes        = mapˢ hash txdats
          inputsDataHashes    = mapPartial (λ txout →  if txOutToP2Script utxo tx txout
                                                       then txOutToDataHash txout