diff --git a/core/rip7560_abi.go b/core/rip7560_abi.go
index 7687dc6926..cc4aaf02f1 100644
--- a/core/rip7560_abi.go
+++ b/core/rip7560_abi.go
@@ -27,14 +27,14 @@ func abiEncodeValidateTransaction(tx *types.Rip7560AccountAbstractionTx, signing
 	}
 
 	txAbiEncoding, err := tx.AbiEncode()
-	validateTransactionData, err := jsonAbi.Pack("validateTransaction", big.NewInt(0), signingHash, txAbiEncoding)
+	validateTransactionData, err := jsonAbi.Pack("validateTransaction", big.NewInt(Rip7560AbiVersion), signingHash, txAbiEncoding)
 	return validateTransactionData, err
 }
 
 func abiEncodeValidatePaymasterTransaction(tx *types.Rip7560AccountAbstractionTx, signingHash common.Hash) ([]byte, error) {
 	jsonAbi, err := abi.JSON(strings.NewReader(ValidatePaymasterTransactionAbi))
 	txAbiEncoding, err := tx.AbiEncode()
-	data, err := jsonAbi.Pack("validatePaymasterTransaction", big.NewInt(0), signingHash, txAbiEncoding)
+	data, err := jsonAbi.Pack("validatePaymasterTransaction", big.NewInt(Rip7560AbiVersion), signingHash, txAbiEncoding)
 	return data, err
 }
 
@@ -43,6 +43,7 @@ func abiEncodePostPaymasterTransaction(context []byte) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	// TODO: pass actual gas cost parameter here!
 	postOpData, err := jsonAbi.Pack("postPaymasterTransaction", true, big.NewInt(0), context)
 	return postOpData, err
 }
diff --git a/core/rip7560_abi_constants.go b/core/rip7560_abi_constants.go
index d4d3f5c02a..1d9bae62f2 100644
--- a/core/rip7560_abi_constants.go
+++ b/core/rip7560_abi_constants.go
@@ -4,6 +4,7 @@ const AcceptAccountMethodSig = uint64(0x1256ebd1)   // acceptAccount(uint256,uin
 const AcceptPaymasterMethodSig = uint64(0x03be8439) // acceptPaymaster(uint256,uint256,bytes)
 const SigFailAccountMethodSig = uint64(0x7715fac2)  // sigFailAccount(uint256,uint256)
 const PaymasterMaxContextSize = 65536
+const Rip7560AbiVersion = 0
 
 const ValidateTransactionAbi = `
 [