diff --git a/core/block_validator.go b/core/block_validator.go
index fdd415d640..136d321c20 100644
--- a/core/block_validator.go
+++ b/core/block_validator.go
@@ -164,11 +164,11 @@ func (v *BlockValidator) ValidateBody(block *types.Block) error {
 func debugGsSummary(gasSummaries map[int]*state.GasSummary, block *types.Block) {
 	for txIndex, s := range gasSummaries {
 		if s == nil {
-			log.Error("GasSummary debug, gs is nil", "blockNumber", block.NumberU64(), "txIndex", txIndex)
-			fmt.Printf("GasSummary, block:%d, txIndex:%d, is nil\n", block.NumberU64(), txIndex)
+			log.Error("[DEBUG invalid gas used], gs is nil", "blockNumber", block.NumberU64(), "txIndex", txIndex)
+			fmt.Printf("[DEBUG invalid gas used], block:%d, txIndex:%d, is nil\n", block.NumberU64(), txIndex)
 		} else {
-			log.Error("GasSummary debug, gs collected", "blockNumber", block.NumberU64(), "txIndex", txIndex, "gasSummary", s.Debug())
-			fmt.Printf("GasSummary, block:%d, txIndex:%d, gasSummary:%s\n", block.NumberU64(), txIndex, s.Debug())
+			log.Error("[DEBUG invalid gas used], gs collected", "blockNumber", block.NumberU64(), "txIndex", txIndex, "gasSummary", s.Debug())
+			fmt.Printf("[DEBUG invalid gas used], block:%d, txIndex:%d, gasSummary:%s\n", block.NumberU64(), txIndex, s.Debug())
 		}
 	}
 }
diff --git a/core/blockchain.go b/core/blockchain.go
index 16b05ccc10..ec0aa2524e 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1949,11 +1949,13 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error)
 
 			// Process block using the parent state as reference point
 			pstart = time.Now()
+			fmt.Printf("[DEBUG invalid gas used] block %d, gas used %d\n", block.NumberU64(), block.GasUsed())
 			receipts, logs, usedGas, err = bc.processor.Process(block, statedb, bc.vmConfig)
 			if err == FallbackToSerialProcessorErr {
 				bc.UseSerialProcessor()
 				receipts, logs, usedGas, err = bc.processor.Process(block, statedb, bc.vmConfig)
 			}
+			fmt.Printf("[DEBUG invalid gas used] block %d, gas used %d\n", block.NumberU64(), block.GasUsed())
 			if err != nil {
 				bc.reportBlock(block, receipts, err)
 				followupInterrupt.Store(true)
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index 73741cbc46..bd48ca72d4 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -17,6 +17,8 @@
 package vm
 
 import (
+	"fmt"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -199,6 +201,7 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 		} else if sLen > operation.maxStack {
 			return nil, &ErrStackOverflow{stackLen: sLen, limit: operation.maxStack}
 		}
+		fmt.Printf("[DEBUG invalid gas used] from:%s, to:%s, op:%s, cost:%d\n", contract.caller.Address(), contract.self.Address(), op.String(), cost)
 		if !contract.UseGas(cost) {
 			return nil, ErrOutOfGas
 		}