diff --git a/eth/api_debug.go b/eth/api_debug.go
index d5e4dda140..188dee11aa 100644
--- a/eth/api_debug.go
+++ b/eth/api_debug.go
@@ -271,26 +271,26 @@ func storageRangeAt(statedb *state.StateDB, root common.Hash, address common.Add
 //
 // With one parameter, returns the list of accounts modified in the specified block.
 func (api *DebugAPI) GetModifiedAccountsByNumber(startNum uint64, endNum *uint64) ([]common.Address, error) {
-	var startBlock, endBlock *types.Block
+	var startHeader, endHeader *types.Header
 
-	startBlock = api.eth.blockchain.GetBlockByNumber(startNum)
-	if startBlock == nil {
+	startHeader = api.eth.blockchain.GetHeaderByNumber(startNum)
+	if startHeader == nil {
 		return nil, fmt.Errorf("start block %x not found", startNum)
 	}
 
 	if endNum == nil {
-		endBlock = startBlock
-		startBlock = api.eth.blockchain.GetBlockByHash(startBlock.ParentHash())
-		if startBlock == nil {
-			return nil, fmt.Errorf("block %x has no parent", endBlock.Number())
+		endHeader = startHeader
+		startHeader = api.eth.blockchain.GetHeaderByHash(startHeader.ParentHash)
+		if startHeader == nil {
+			return nil, fmt.Errorf("block %x has no parent", endHeader.Number)
 		}
 	} else {
-		endBlock = api.eth.blockchain.GetBlockByNumber(*endNum)
-		if endBlock == nil {
+		endHeader = api.eth.blockchain.GetHeaderByNumber(*endNum)
+		if endHeader == nil {
 			return nil, fmt.Errorf("end block %d not found", *endNum)
 		}
 	}
-	return api.getModifiedAccounts(startBlock, endBlock)
+	return api.getModifiedAccounts(startHeader, endHeader)
 }
 
 // GetModifiedAccountsByHash returns all accounts that have changed between the
@@ -299,38 +299,38 @@ func (api *DebugAPI) GetModifiedAccountsByNumber(startNum uint64, endNum *uint64
 //
 // With one parameter, returns the list of accounts modified in the specified block.
 func (api *DebugAPI) GetModifiedAccountsByHash(startHash common.Hash, endHash *common.Hash) ([]common.Address, error) {
-	var startBlock, endBlock *types.Block
-	startBlock = api.eth.blockchain.GetBlockByHash(startHash)
-	if startBlock == nil {
+	var startHeader, endHeader *types.Header
+	startHeader = api.eth.blockchain.GetHeaderByHash(startHash)
+	if startHeader == nil {
 		return nil, fmt.Errorf("start block %x not found", startHash)
 	}
 
 	if endHash == nil {
-		endBlock = startBlock
-		startBlock = api.eth.blockchain.GetBlockByHash(startBlock.ParentHash())
-		if startBlock == nil {
-			return nil, fmt.Errorf("block %x has no parent", endBlock.Number())
+		endHeader = startHeader
+		startHeader = api.eth.blockchain.GetHeaderByHash(startHeader.ParentHash)
+		if startHeader == nil {
+			return nil, fmt.Errorf("block %x has no parent", endHeader.Number)
 		}
 	} else {
-		endBlock = api.eth.blockchain.GetBlockByHash(*endHash)
-		if endBlock == nil {
+		endHeader = api.eth.blockchain.GetHeaderByHash(*endHash)
+		if endHeader == nil {
 			return nil, fmt.Errorf("end block %x not found", *endHash)
 		}
 	}
-	return api.getModifiedAccounts(startBlock, endBlock)
+	return api.getModifiedAccounts(startHeader, endHeader)
 }
 
-func (api *DebugAPI) getModifiedAccounts(startBlock, endBlock *types.Block) ([]common.Address, error) {
-	if startBlock.Number().Uint64() >= endBlock.Number().Uint64() {
-		return nil, fmt.Errorf("start block height (%d) must be less than end block height (%d)", startBlock.Number().Uint64(), endBlock.Number().Uint64())
+func (api *DebugAPI) getModifiedAccounts(startHeader, endHeader *types.Header) ([]common.Address, error) {
+	if startHeader.Number.Uint64() >= endHeader.Number.Uint64() {
+		return nil, fmt.Errorf("start block height (%d) must be less than end block height (%d)", startHeader.Number.Uint64(), endHeader.Number.Uint64())
 	}
 	triedb := api.eth.BlockChain().TrieDB()
 
-	oldTrie, err := trie.NewStateTrie(trie.StateTrieID(startBlock.Root()), triedb)
+	oldTrie, err := trie.NewStateTrie(trie.StateTrieID(startHeader.Root), triedb)
 	if err != nil {
 		return nil, err
 	}
-	newTrie, err := trie.NewStateTrie(trie.StateTrieID(endBlock.Root()), triedb)
+	newTrie, err := trie.NewStateTrie(trie.StateTrieID(endHeader.Root), triedb)
 	if err != nil {
 		return nil, err
 	}