diff --git a/core/state_transition.go b/core/state_transition.go
index 9c4f76d1c5..64c8abb7ed 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -234,7 +234,7 @@ func (st *StateTransition) to() common.Address {
 
 func (st *StateTransition) buyGas() error {
 	mgval := new(big.Int).SetUint64(st.msg.GasLimit)
-	mgval = mgval.Mul(mgval, st.msg.GasPrice)
+	mgval.Mul(mgval, st.msg.GasPrice)
 	balanceCheck := new(big.Int).Set(mgval)
 	if st.msg.GasFeeCap != nil {
 		balanceCheck.SetUint64(st.msg.GasLimit)