diff --git a/cmd/clef/main.go b/cmd/clef/main.go
index a90031245905..06c034a5545e 100644
--- a/cmd/clef/main.go
+++ b/cmd/clef/main.go
@@ -690,7 +690,7 @@ func testExternalUI(api *core.SignerAPI) {
 			big.NewInt(1337),
 			1338,
 			1338,
-			big.NewInt(1338),
+			1338,
 			[]byte("Extra data Extra data Extra data  Extra data  Extra data  Extra data  Extra data Extra data"),
 			common.HexToHash("0x0000H45H"),
 			types.BlockNonce{},
diff --git a/cmd/faucet/faucet.go b/cmd/faucet/faucet.go
index 5e4b77a6a543..78b4a6563484 100644
--- a/cmd/faucet/faucet.go
+++ b/cmd/faucet/faucet.go
@@ -579,7 +579,7 @@ func (f *faucet) loop() {
 	go func() {
 		for head := range update {
 			// New chain head arrived, query the current stats and stream to clients
-			timestamp := time.Unix(head.Time.Int64(), 0)
+			timestamp := time.Unix(int64(head.Time), 0)
 			if time.Since(timestamp) > time.Hour {
 				log.Warn("Skipping faucet refresh, head too old", "number", head.Number, "hash", head.Hash(), "age", common.PrettyAge(timestamp))
 				continue
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index 0763a9ed3b5c..3d96de31281e 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -365,7 +365,7 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 				if !ok {
 					continue
 				}
-				if timestamp := time.Unix(done.Latest.Time.Int64(), 0); time.Since(timestamp) < 10*time.Minute {
+				if timestamp := time.Unix(int64(done.Latest.Time), 0); time.Since(timestamp) < 10*time.Minute {
 					log.Info("Synchronisation completed", "latestnum", done.Latest.Number, "latesthash", done.Latest.Hash(),
 						"age", common.PrettyAge(timestamp))
 					stack.Stop()
diff --git a/consensus/clique/clique.go b/consensus/clique/clique.go
index 967a843dec59..6bdee6dd5f56 100644
--- a/consensus/clique/clique.go
+++ b/consensus/clique/clique.go
@@ -249,7 +249,7 @@ func (c *Clique) verifyHeader(chain consensus.ChainReader, header *types.Header,
 	number := header.Number.Uint64()
 
 	// Don't waste time checking blocks from the future
-	if header.Time.Cmp(big.NewInt(time.Now().Unix())) > 0 {
+	if header.Time > uint64(time.Now().Unix()) {
 		return consensus.ErrFutureBlock
 	}
 	// Checkpoint blocks need to enforce zero beneficiary
@@ -321,7 +321,7 @@ func (c *Clique) verifyCascadingFields(chain consensus.ChainReader, header *type
 	if parent == nil || parent.Number.Uint64() != number-1 || parent.Hash() != header.ParentHash {
 		return consensus.ErrUnknownAncestor
 	}
-	if parent.Time.Uint64()+c.config.Period > header.Time.Uint64() {
+	if parent.Time+c.config.Period > header.Time {
 		return ErrInvalidTimestamp
 	}
 	// Retrieve the snapshot needed to verify this header and cache it
@@ -540,9 +540,9 @@ func (c *Clique) Prepare(chain consensus.ChainReader, header *types.Header) erro
 	if parent == nil {
 		return consensus.ErrUnknownAncestor
 	}
-	header.Time = new(big.Int).Add(parent.Time, new(big.Int).SetUint64(c.config.Period))
-	if header.Time.Int64() < time.Now().Unix() {
-		header.Time = big.NewInt(time.Now().Unix())
+	header.Time = parent.Time + c.config.Period
+	if header.Time < uint64(time.Now().Unix()) {
+		header.Time = uint64(time.Now().Unix())
 	}
 	return nil
 }
@@ -607,7 +607,7 @@ func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, results c
 		}
 	}
 	// Sweet, the protocol permits us to sign the block, wait for our time
-	delay := time.Unix(header.Time.Int64(), 0).Sub(time.Now()) // nolint: gosimple
+	delay := time.Unix(int64(header.Time), 0).Sub(time.Now()) // nolint: gosimple
 	if header.Difficulty.Cmp(diffNoTurn) == 0 {
 		// It's not our turn explicitly to sign, delay it a bit
 		wiggle := time.Duration(len(snap.Signers)/2+1) * wiggleTime
diff --git a/consensus/ethash/algorithm_test.go b/consensus/ethash/algorithm_test.go
index c58479e2896c..cf8552f3ab74 100644
--- a/consensus/ethash/algorithm_test.go
+++ b/consensus/ethash/algorithm_test.go
@@ -716,7 +716,7 @@ func TestConcurrentDiskCacheGeneration(t *testing.T) {
 		Difficulty:  big.NewInt(167925187834220),
 		GasLimit:    4015682,
 		GasUsed:     0,
-		Time:        big.NewInt(1488928920),
+		Time:        1488928920,
 		Extra:       []byte("www.bw.com"),
 		MixDigest:   common.HexToHash("0x3e140b0784516af5e5ec6730f2fb20cca22f32be399b9e4ad77d32541f798cd0"),
 		Nonce:       types.EncodeNonce(0xf400cd0006070c49),
diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go
index 62e3f8fca974..fb9a396ae4a7 100644
--- a/consensus/ethash/consensus.go
+++ b/consensus/ethash/consensus.go
@@ -63,7 +63,6 @@ var (
 // codebase, inherently breaking if the engine is swapped out. Please put common
 // error types into the consensus package.
 var (
-	errLargeBlockTime    = errors.New("timestamp too big")
 	errZeroBlockTime     = errors.New("timestamp equals parent's")
 	errTooManyUncles     = errors.New("too many uncles")
 	errDuplicateUncle    = errors.New("duplicate uncle")
@@ -242,20 +241,16 @@ func (ethash *Ethash) verifyHeader(chain consensus.ChainReader, header, parent *
 		return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)
 	}
 	// Verify the header's timestamp
-	if uncle {
-		if header.Time.Cmp(math.MaxBig256) > 0 {
-			return errLargeBlockTime
-		}
-	} else {
-		if header.Time.Cmp(big.NewInt(time.Now().Add(allowedFutureBlockTime).Unix())) > 0 {
+	if !uncle {
+		if header.Time > uint64(time.Now().Add(allowedFutureBlockTime).Unix()) {
 			return consensus.ErrFutureBlock
 		}
 	}
-	if header.Time.Cmp(parent.Time) <= 0 {
+	if header.Time <= parent.Time {
 		return errZeroBlockTime
 	}
 	// Verify the block's difficulty based in it's timestamp and parent's difficulty
-	expected := ethash.CalcDifficulty(chain, header.Time.Uint64(), parent)
+	expected := ethash.CalcDifficulty(chain, header.Time, parent)
 
 	if expected.Cmp(header.Difficulty) != 0 {
 		return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)
@@ -349,7 +344,7 @@ func makeDifficultyCalculator(bombDelay *big.Int) func(time uint64, parent *type
 		//        ) + 2^(periodCount - 2)
 
 		bigTime := new(big.Int).SetUint64(time)
-		bigParentTime := new(big.Int).Set(parent.Time)
+		bigParentTime := new(big.Int).SetUint64(parent.Time)
 
 		// holds intermediate values to make the algo easier to read & audit
 		x := new(big.Int)
@@ -408,7 +403,7 @@ func calcDifficultyHomestead(time uint64, parent *types.Header) *big.Int {
 	//        ) + 2^(periodCount - 2)
 
 	bigTime := new(big.Int).SetUint64(time)
-	bigParentTime := new(big.Int).Set(parent.Time)
+	bigParentTime := new(big.Int).SetUint64(parent.Time)
 
 	// holds intermediate values to make the algo easier to read & audit
 	x := new(big.Int)
@@ -456,7 +451,7 @@ func calcDifficultyFrontier(time uint64, parent *types.Header) *big.Int {
 	bigParentTime := new(big.Int)
 
 	bigTime.SetUint64(time)
-	bigParentTime.Set(parent.Time)
+	bigParentTime.SetUint64(parent.Time)
 
 	if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
 		diff.Add(parent.Difficulty, adjust)
@@ -558,7 +553,7 @@ func (ethash *Ethash) Prepare(chain consensus.ChainReader, header *types.Header)
 	if parent == nil {
 		return consensus.ErrUnknownAncestor
 	}
-	header.Difficulty = ethash.CalcDifficulty(chain, header.Time.Uint64(), parent)
+	header.Difficulty = ethash.CalcDifficulty(chain, header.Time, parent)
 	return nil
 }
 
diff --git a/consensus/ethash/consensus_test.go b/consensus/ethash/consensus_test.go
index 438a99dd66c2..675737d9e1aa 100644
--- a/consensus/ethash/consensus_test.go
+++ b/consensus/ethash/consensus_test.go
@@ -76,7 +76,7 @@ func TestCalcDifficulty(t *testing.T) {
 		number := new(big.Int).Sub(test.CurrentBlocknumber, big.NewInt(1))
 		diff := CalcDifficulty(config, test.CurrentTimestamp, &types.Header{
 			Number:     number,
-			Time:       new(big.Int).SetUint64(test.ParentTimestamp),
+			Time:       test.ParentTimestamp,
 			Difficulty: test.ParentDifficulty,
 		})
 		if diff.Cmp(test.CurrentDifficulty) != 0 {
diff --git a/core/blockchain.go b/core/blockchain.go
index dd3edeb45b47..20ab71b4d7da 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -288,9 +288,9 @@ func (bc *BlockChain) loadLastState() error {
 	blockTd := bc.GetTd(currentBlock.Hash(), currentBlock.NumberU64())
 	fastTd := bc.GetTd(currentFastBlock.Hash(), currentFastBlock.NumberU64())
 
-	log.Info("Loaded most recent local header", "number", currentHeader.Number, "hash", currentHeader.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(currentHeader.Time.Int64(), 0)))
-	log.Info("Loaded most recent local full block", "number", currentBlock.Number(), "hash", currentBlock.Hash(), "td", blockTd, "age", common.PrettyAge(time.Unix(currentBlock.Time().Int64(), 0)))
-	log.Info("Loaded most recent local fast block", "number", currentFastBlock.Number(), "hash", currentFastBlock.Hash(), "td", fastTd, "age", common.PrettyAge(time.Unix(currentFastBlock.Time().Int64(), 0)))
+	log.Info("Loaded most recent local header", "number", currentHeader.Number, "hash", currentHeader.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(int64(currentHeader.Time), 0)))
+	log.Info("Loaded most recent local full block", "number", currentBlock.Number(), "hash", currentBlock.Hash(), "td", blockTd, "age", common.PrettyAge(time.Unix(int64(currentBlock.Time()), 0)))
+	log.Info("Loaded most recent local fast block", "number", currentFastBlock.Number(), "hash", currentFastBlock.Hash(), "td", fastTd, "age", common.PrettyAge(time.Unix(int64(currentFastBlock.Time()), 0)))
 
 	return nil
 }
@@ -904,7 +904,7 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 
 	context := []interface{}{
 		"count", stats.processed, "elapsed", common.PrettyDuration(time.Since(start)),
-		"number", head.Number(), "hash", head.Hash(), "age", common.PrettyAge(time.Unix(head.Time().Int64(), 0)),
+		"number", head.Number(), "hash", head.Hash(), "age", common.PrettyAge(time.Unix(int64(head.Time()), 0)),
 		"size", common.StorageSize(bytes),
 	}
 	if stats.ignored > 0 {
@@ -1074,8 +1074,8 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 // accepted for future processing, and returns an error if the block is too far
 // ahead and was not added.
 func (bc *BlockChain) addFutureBlock(block *types.Block) error {
-	max := big.NewInt(time.Now().Unix() + maxTimeFutureBlocks)
-	if block.Time().Cmp(max) > 0 {
+	max := uint64(time.Now().Unix() + maxTimeFutureBlocks)
+	if block.Time() > max {
 		return fmt.Errorf("future block timestamp %v > allowed %v", block.Time(), max)
 	}
 	bc.futureBlocks.Add(block.Hash(), block)
diff --git a/core/blockchain_insert.go b/core/blockchain_insert.go
index e4d758d4c64e..5685b0a4bdd9 100644
--- a/core/blockchain_insert.go
+++ b/core/blockchain_insert.go
@@ -60,7 +60,7 @@ func (st *insertStats) report(chain []*types.Block, index int, dirty common.Stor
 			"elapsed", common.PrettyDuration(elapsed), "mgasps", float64(st.usedGas) * 1000 / float64(elapsed),
 			"number", end.Number(), "hash", end.Hash(),
 		}
-		if timestamp := time.Unix(end.Time().Int64(), 0); time.Since(timestamp) > time.Minute {
+		if timestamp := time.Unix(int64(end.Time()), 0); time.Since(timestamp) > time.Minute {
 			context = append(context, []interface{}{"age", common.PrettyAge(timestamp)}...)
 		}
 		context = append(context, []interface{}{"dirty", dirty}...)
diff --git a/core/chain_makers.go b/core/chain_makers.go
index 0b5a3d1843a9..d563d85eeeb4 100644
--- a/core/chain_makers.go
+++ b/core/chain_makers.go
@@ -149,12 +149,12 @@ func (b *BlockGen) PrevBlock(index int) *types.Block {
 // associated difficulty. It's useful to test scenarios where forking is not
 // tied to chain length directly.
 func (b *BlockGen) OffsetTime(seconds int64) {
-	b.header.Time.Add(b.header.Time, big.NewInt(seconds))
-	if b.header.Time.Cmp(b.parent.Header().Time) <= 0 {
+	b.header.Time += uint64(seconds)
+	if b.header.Time <= b.parent.Header().Time {
 		panic("block time out of range")
 	}
 	chainreader := &fakeChainReader{config: b.config}
-	b.header.Difficulty = b.engine.CalcDifficulty(chainreader, b.header.Time.Uint64(), b.parent.Header())
+	b.header.Difficulty = b.engine.CalcDifficulty(chainreader, b.header.Time, b.parent.Header())
 }
 
 // GenerateChain creates a chain of n blocks. The first block's
@@ -225,20 +225,20 @@ func GenerateChain(config *params.ChainConfig, parent *types.Block, engine conse
 }
 
 func makeHeader(chain consensus.ChainReader, parent *types.Block, state *state.StateDB, engine consensus.Engine) *types.Header {
-	var time *big.Int
-	if parent.Time() == nil {
-		time = big.NewInt(10)
+	var time uint64
+	if parent.Time() == 0 {
+		time = 10
 	} else {
-		time = new(big.Int).Add(parent.Time(), big.NewInt(10)) // block time is fixed at 10 seconds
+		time = parent.Time() + 10 // block time is fixed at 10 seconds
 	}
 
 	return &types.Header{
 		Root:       state.IntermediateRoot(chain.Config().IsEIP158(parent.Number())),
 		ParentHash: parent.Hash(),
 		Coinbase:   parent.Coinbase(),
-		Difficulty: engine.CalcDifficulty(chain, time.Uint64(), &types.Header{
+		Difficulty: engine.CalcDifficulty(chain, time, &types.Header{
 			Number:     parent.Number(),
-			Time:       new(big.Int).Sub(time, big.NewInt(10)),
+			Time:       time - 10,
 			Difficulty: parent.Difficulty(),
 			UncleHash:  parent.UncleHash(),
 		}),
diff --git a/core/evm.go b/core/evm.go
index d303c40a4074..b654bbd4796f 100644
--- a/core/evm.go
+++ b/core/evm.go
@@ -51,7 +51,7 @@ func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author
 		Origin:      msg.From(),
 		Coinbase:    beneficiary,
 		BlockNumber: new(big.Int).Set(header.Number),
-		Time:        new(big.Int).Set(header.Time),
+		Time:        new(big.Int).SetUint64(header.Time),
 		Difficulty:  new(big.Int).Set(header.Difficulty),
 		GasLimit:    header.GasLimit,
 		GasPrice:    new(big.Int).Set(msg.GasPrice()),
diff --git a/core/genesis.go b/core/genesis.go
index 4aa129966ffa..1f34a3a9ea64 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -243,7 +243,7 @@ func (g *Genesis) ToBlock(db ethdb.Database) *types.Block {
 	head := &types.Header{
 		Number:     new(big.Int).SetUint64(g.Number),
 		Nonce:      types.EncodeNonce(g.Nonce),
-		Time:       new(big.Int).SetUint64(g.Timestamp),
+		Time:       g.Timestamp,
 		ParentHash: g.ParentHash,
 		Extra:      g.ExtraData,
 		GasLimit:   g.GasLimit,
diff --git a/core/headerchain.go b/core/headerchain.go
index f005b8324cbe..d0c1987fb5e1 100644
--- a/core/headerchain.go
+++ b/core/headerchain.go
@@ -290,7 +290,7 @@ func (hc *HeaderChain) InsertHeaderChain(chain []*types.Header, writeHeader WhCa
 		"count", stats.processed, "elapsed", common.PrettyDuration(time.Since(start)),
 		"number", last.Number, "hash", last.Hash(),
 	}
-	if timestamp := time.Unix(last.Time.Int64(), 0); time.Since(timestamp) > time.Minute {
+	if timestamp := time.Unix(int64(last.Time), 0); time.Since(timestamp) > time.Minute {
 		context = append(context, []interface{}{"age", common.PrettyAge(timestamp)}...)
 	}
 	if stats.ignored > 0 {
diff --git a/core/types/block.go b/core/types/block.go
index b84e13c65ad9..d611885f1ac4 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -79,7 +79,7 @@ type Header struct {
 	Number      *big.Int       `json:"number"           gencodec:"required"`
 	GasLimit    uint64         `json:"gasLimit"         gencodec:"required"`
 	GasUsed     uint64         `json:"gasUsed"          gencodec:"required"`
-	Time        *big.Int       `json:"timestamp"        gencodec:"required"`
+	Time        uint64         `json:"timestamp"        gencodec:"required"`
 	Extra       []byte         `json:"extraData"        gencodec:"required"`
 	MixDigest   common.Hash    `json:"mixHash"`
 	Nonce       BlockNonce     `json:"nonce"`
@@ -91,7 +91,7 @@ type headerMarshaling struct {
 	Number     *hexutil.Big
 	GasLimit   hexutil.Uint64
 	GasUsed    hexutil.Uint64
-	Time       *hexutil.Big
+	Time       hexutil.Uint64
 	Extra      hexutil.Bytes
 	Hash       common.Hash `json:"hash"` // adds call to Hash() in MarshalJSON
 }
@@ -107,7 +107,7 @@ var headerSize = common.StorageSize(reflect.TypeOf(Header{}).Size())
 // Size returns the approximate memory used by all internal contents. It is used
 // to approximate and limit the memory consumption of various caches.
 func (h *Header) Size() common.StorageSize {
-	return headerSize + common.StorageSize(len(h.Extra)+(h.Difficulty.BitLen()+h.Number.BitLen()+h.Time.BitLen())/8)
+	return headerSize + common.StorageSize(len(h.Extra)+(h.Difficulty.BitLen()+h.Number.BitLen())/8)
 }
 
 func rlpHash(x interface{}) (h common.Hash) {
@@ -223,9 +223,6 @@ func NewBlockWithHeader(header *Header) *Block {
 // modifying a header variable.
 func CopyHeader(h *Header) *Header {
 	cpy := *h
-	if cpy.Time = new(big.Int); h.Time != nil {
-		cpy.Time.Set(h.Time)
-	}
 	if cpy.Difficulty = new(big.Int); h.Difficulty != nil {
 		cpy.Difficulty.Set(h.Difficulty)
 	}
@@ -288,7 +285,7 @@ func (b *Block) Number() *big.Int     { return new(big.Int).Set(b.header.Number)
 func (b *Block) GasLimit() uint64     { return b.header.GasLimit }
 func (b *Block) GasUsed() uint64      { return b.header.GasUsed }
 func (b *Block) Difficulty() *big.Int { return new(big.Int).Set(b.header.Difficulty) }
-func (b *Block) Time() *big.Int       { return new(big.Int).Set(b.header.Time) }
+func (b *Block) Time() uint64         { return b.header.Time }
 
 func (b *Block) NumberU64() uint64        { return b.header.Number.Uint64() }
 func (b *Block) MixDigest() common.Hash   { return b.header.MixDigest }
diff --git a/core/types/block_test.go b/core/types/block_test.go
index a35fbc25b1ed..2576f2fbc802 100644
--- a/core/types/block_test.go
+++ b/core/types/block_test.go
@@ -48,7 +48,7 @@ func TestBlockEncoding(t *testing.T) {
 	check("Root", block.Root(), common.HexToHash("ef1552a40b7165c3cd773806b9e0c165b75356e0314bf0706f279c729f51e017"))
 	check("Hash", block.Hash(), common.HexToHash("0a5843ac1cb04865017cb35a57b50b07084e5fcee39b5acadade33149f4fff9e"))
 	check("Nonce", block.Nonce(), uint64(0xa13a5a8c8f2bb1c4))
-	check("Time", block.Time(), big.NewInt(1426516743))
+	check("Time", block.Time(), uint64(1426516743))
 	check("Size", block.Size(), common.StorageSize(len(blockEnc)))
 
 	tx1 := NewTransaction(0, common.HexToAddress("095e7baea6a6c7c4c2dfeb977efac326af552d87"), big.NewInt(10), 50000, big.NewInt(10), nil)
diff --git a/core/types/gen_header_json.go b/core/types/gen_header_json.go
index 59a1c9c439b4..4212b8d94d25 100644
--- a/core/types/gen_header_json.go
+++ b/core/types/gen_header_json.go
@@ -27,7 +27,7 @@ func (h Header) MarshalJSON() ([]byte, error) {
 		Number      *hexutil.Big   `json:"number"           gencodec:"required"`
 		GasLimit    hexutil.Uint64 `json:"gasLimit"         gencodec:"required"`
 		GasUsed     hexutil.Uint64 `json:"gasUsed"          gencodec:"required"`
-		Time        *hexutil.Big   `json:"timestamp"        gencodec:"required"`
+		Time        hexutil.Uint64 `json:"timestamp"        gencodec:"required"`
 		Extra       hexutil.Bytes  `json:"extraData"        gencodec:"required"`
 		MixDigest   common.Hash    `json:"mixHash"`
 		Nonce       BlockNonce     `json:"nonce"`
@@ -45,7 +45,7 @@ func (h Header) MarshalJSON() ([]byte, error) {
 	enc.Number = (*hexutil.Big)(h.Number)
 	enc.GasLimit = hexutil.Uint64(h.GasLimit)
 	enc.GasUsed = hexutil.Uint64(h.GasUsed)
-	enc.Time = (*hexutil.Big)(h.Time)
+	enc.Time = hexutil.Uint64(h.Time)
 	enc.Extra = h.Extra
 	enc.MixDigest = h.MixDigest
 	enc.Nonce = h.Nonce
@@ -67,7 +67,7 @@ func (h *Header) UnmarshalJSON(input []byte) error {
 		Number      *hexutil.Big    `json:"number"           gencodec:"required"`
 		GasLimit    *hexutil.Uint64 `json:"gasLimit"         gencodec:"required"`
 		GasUsed     *hexutil.Uint64 `json:"gasUsed"          gencodec:"required"`
-		Time        *hexutil.Big    `json:"timestamp"        gencodec:"required"`
+		Time        *hexutil.Uint64 `json:"timestamp"        gencodec:"required"`
 		Extra       *hexutil.Bytes  `json:"extraData"        gencodec:"required"`
 		MixDigest   *common.Hash    `json:"mixHash"`
 		Nonce       *BlockNonce     `json:"nonce"`
@@ -123,7 +123,7 @@ func (h *Header) UnmarshalJSON(input []byte) error {
 	if dec.Time == nil {
 		return errors.New("missing required field 'timestamp' for Header")
 	}
-	h.Time = (*big.Int)(dec.Time)
+	h.Time = uint64(*dec.Time)
 	if dec.Extra == nil {
 		return errors.New("missing required field 'extraData' for Header")
 	}
diff --git a/ethstats/ethstats.go b/ethstats/ethstats.go
index 9f3d7237e9b8..caf232097a7f 100644
--- a/ethstats/ethstats.go
+++ b/ethstats/ethstats.go
@@ -557,7 +557,7 @@ func (s *Service) assembleBlockStats(block *types.Block) *blockStats {
 		Number:     header.Number,
 		Hash:       header.Hash(),
 		ParentHash: header.ParentHash,
-		Timestamp:  header.Time,
+		Timestamp:  new(big.Int).SetUint64(header.Time),
 		Miner:      author,
 		GasUsed:    header.GasUsed,
 		GasLimit:   header.GasLimit,
diff --git a/graphql/graphql.go b/graphql/graphql.go
index b16f93e463b1..b3bcbd8a43e2 100644
--- a/graphql/graphql.go
+++ b/graphql/graphql.go
@@ -512,12 +512,12 @@ func (b *Block) Difficulty(ctx context.Context) (hexutil.Big, error) {
 	return hexutil.Big(*header.Difficulty), nil
 }
 
-func (b *Block) Timestamp(ctx context.Context) (hexutil.Big, error) {
+func (b *Block) Timestamp(ctx context.Context) (hexutil.Uint64, error) {
 	header, err := b.resolveHeader(ctx)
 	if err != nil {
-		return hexutil.Big{}, err
+		return 0, err
 	}
-	return hexutil.Big(*header.Time), nil
+	return hexutil.Uint64(header.Time), nil
 }
 
 func (b *Block) Nonce(ctx context.Context) (hexutil.Bytes, error) {
diff --git a/graphql/schema.go b/graphql/schema.go
index e266e429e1e6..bd913d9aa654 100644
--- a/graphql/schema.go
+++ b/graphql/schema.go
@@ -165,7 +165,7 @@ const schema string = `
         # GasUsed is the amount of gas that was used executing transactions in this block.
         gasUsed: Long!
         # Timestamp is the unix timestamp at which this block was mined.
-        timestamp: BigInt!
+        timestamp: Long!
         # LogsBloom is a bloom filter that can be used to check if a block may
         # contain log entries matching a filter.
         logsBloom: Bytes!
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index e85e6d20ac73..b6f01b7539de 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -883,7 +883,7 @@ func RPCMarshalBlock(b *types.Block, inclTx bool, fullTx bool) (map[string]inter
 		"size":             hexutil.Uint64(b.Size()),
 		"gasLimit":         hexutil.Uint64(head.GasLimit),
 		"gasUsed":          hexutil.Uint64(head.GasUsed),
-		"timestamp":        (*hexutil.Big)(head.Time),
+		"timestamp":        hexutil.Uint64(head.Time),
 		"transactionsRoot": head.TxHash,
 		"receiptsRoot":     head.ReceiptHash,
 	}
diff --git a/light/lightchain.go b/light/lightchain.go
index 38f1f634180b..80aeb0850d14 100644
--- a/light/lightchain.go
+++ b/light/lightchain.go
@@ -158,7 +158,7 @@ func (lc *LightChain) loadLastState() error {
 	// Issue a status log and return
 	header := lc.hc.CurrentHeader()
 	headerTd := lc.GetTd(header.Hash(), header.Number.Uint64())
-	log.Info("Loaded most recent local header", "number", header.Number, "hash", header.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(header.Time.Int64(), 0)))
+	log.Info("Loaded most recent local header", "number", header.Number, "hash", header.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(int64(header.Time), 0)))
 
 	return nil
 }
@@ -485,7 +485,7 @@ func (lc *LightChain) SyncCht(ctx context.Context) bool {
 
 		// Ensure the chain didn't move past the latest block while retrieving it
 		if lc.hc.CurrentHeader().Number.Uint64() < header.Number.Uint64() {
-			log.Info("Updated latest header based on CHT", "number", header.Number, "hash", header.Hash(), "age", common.PrettyAge(time.Unix(header.Time.Int64(), 0)))
+			log.Info("Updated latest header based on CHT", "number", header.Number, "hash", header.Hash(), "age", common.PrettyAge(time.Unix(int64(header.Time), 0)))
 			lc.hc.SetCurrentHeader(header)
 		}
 		return true
diff --git a/miner/worker.go b/miner/worker.go
index 80c1771b6dee..a9e440aec510 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -828,8 +828,8 @@ func (w *worker) commitNewWork(interrupt *int32, noempty bool, timestamp int64)
 	tstart := time.Now()
 	parent := w.chain.CurrentBlock()
 
-	if parent.Time().Cmp(new(big.Int).SetInt64(timestamp)) >= 0 {
-		timestamp = parent.Time().Int64() + 1
+	if parent.Time() >= uint64(timestamp) {
+		timestamp = int64(parent.Time() + 1)
 	}
 	// this will ensure we're not going off too far in the future
 	if now := time.Now().Unix(); timestamp > now+1 {
@@ -844,7 +844,7 @@ func (w *worker) commitNewWork(interrupt *int32, noempty bool, timestamp int64)
 		Number:     num.Add(num, common.Big1),
 		GasLimit:   core.CalcGasLimit(parent, w.gasFloor, w.gasCeil),
 		Extra:      w.extra,
-		Time:       big.NewInt(timestamp),
+		Time:       uint64(timestamp),
 	}
 	// Only set the coinbase if our consensus engine is running (avoid spurious block rewards)
 	if w.isRunning() {
diff --git a/mobile/types.go b/mobile/types.go
index 1a0389cb5423..b9c44c25d7a9 100644
--- a/mobile/types.go
+++ b/mobile/types.go
@@ -109,7 +109,7 @@ func (h *Header) GetDifficulty() *BigInt { return &BigInt{h.header.Difficulty} }
 func (h *Header) GetNumber() int64       { return h.header.Number.Int64() }
 func (h *Header) GetGasLimit() int64     { return int64(h.header.GasLimit) }
 func (h *Header) GetGasUsed() int64      { return int64(h.header.GasUsed) }
-func (h *Header) GetTime() int64         { return h.header.Time.Int64() }
+func (h *Header) GetTime() int64         { return int64(h.header.Time) }
 func (h *Header) GetExtra() []byte       { return h.header.Extra }
 func (h *Header) GetMixDigest() *Hash    { return &Hash{h.header.MixDigest} }
 func (h *Header) GetNonce() *Nonce       { return &Nonce{h.header.Nonce} }
@@ -180,7 +180,7 @@ func (b *Block) GetDifficulty() *BigInt         { return &BigInt{b.block.Difficu
 func (b *Block) GetNumber() int64               { return b.block.Number().Int64() }
 func (b *Block) GetGasLimit() int64             { return int64(b.block.GasLimit()) }
 func (b *Block) GetGasUsed() int64              { return int64(b.block.GasUsed()) }
-func (b *Block) GetTime() int64                 { return b.block.Time().Int64() }
+func (b *Block) GetTime() int64                 { return int64(b.block.Time()) }
 func (b *Block) GetExtra() []byte               { return b.block.Extra() }
 func (b *Block) GetMixDigest() *Hash            { return &Hash{b.block.MixDigest()} }
 func (b *Block) GetNonce() int64                { return int64(b.block.Nonce()) }
diff --git a/tests/block_test_util.go b/tests/block_test_util.go
index d40a3726c03a..81dd7b1d042a 100644
--- a/tests/block_test_util.go
+++ b/tests/block_test_util.go
@@ -82,7 +82,7 @@ type btHeader struct {
 	Difficulty       *big.Int
 	GasLimit         uint64
 	GasUsed          uint64
-	Timestamp        *big.Int
+	Timestamp        uint64
 }
 
 type btHeaderMarshaling struct {
@@ -91,7 +91,7 @@ type btHeaderMarshaling struct {
 	Difficulty *math.HexOrDecimal256
 	GasLimit   math.HexOrDecimal64
 	GasUsed    math.HexOrDecimal64
-	Timestamp  *math.HexOrDecimal256
+	Timestamp  math.HexOrDecimal64
 }
 
 func (t *BlockTest) Run() error {
@@ -146,7 +146,7 @@ func (t *BlockTest) genesis(config *params.ChainConfig) *core.Genesis {
 	return &core.Genesis{
 		Config:     config,
 		Nonce:      t.json.Genesis.Nonce.Uint64(),
-		Timestamp:  t.json.Genesis.Timestamp.Uint64(),
+		Timestamp:  t.json.Genesis.Timestamp,
 		ParentHash: t.json.Genesis.ParentHash,
 		ExtraData:  t.json.Genesis.ExtraData,
 		GasLimit:   t.json.Genesis.GasLimit,
@@ -248,7 +248,7 @@ func validateHeader(h *btHeader, h2 *types.Header) error {
 	if h.GasUsed != h2.GasUsed {
 		return fmt.Errorf("GasUsed: want: %d have: %d", h.GasUsed, h2.GasUsed)
 	}
-	if h.Timestamp.Cmp(h2.Time) != 0 {
+	if h.Timestamp != h2.Time {
 		return fmt.Errorf("Timestamp: want: %v have: %v", h.Timestamp, h2.Time)
 	}
 	return nil
diff --git a/tests/difficulty_test_util.go b/tests/difficulty_test_util.go
index 00d699cf759f..fe6e90b027f2 100644
--- a/tests/difficulty_test_util.go
+++ b/tests/difficulty_test_util.go
@@ -30,18 +30,18 @@ import (
 //go:generate gencodec -type DifficultyTest -field-override difficultyTestMarshaling -out gen_difficultytest.go
 
 type DifficultyTest struct {
-	ParentTimestamp    *big.Int    `json:"parentTimestamp"`
+	ParentTimestamp    uint64      `json:"parentTimestamp"`
 	ParentDifficulty   *big.Int    `json:"parentDifficulty"`
 	UncleHash          common.Hash `json:"parentUncles"`
-	CurrentTimestamp   *big.Int    `json:"currentTimestamp"`
+	CurrentTimestamp   uint64      `json:"currentTimestamp"`
 	CurrentBlockNumber uint64      `json:"currentBlockNumber"`
 	CurrentDifficulty  *big.Int    `json:"currentDifficulty"`
 }
 
 type difficultyTestMarshaling struct {
-	ParentTimestamp    *math.HexOrDecimal256
+	ParentTimestamp    math.HexOrDecimal64
 	ParentDifficulty   *math.HexOrDecimal256
-	CurrentTimestamp   *math.HexOrDecimal256
+	CurrentTimestamp   math.HexOrDecimal64
 	CurrentDifficulty  *math.HexOrDecimal256
 	UncleHash          common.Hash
 	CurrentBlockNumber math.HexOrDecimal64
@@ -56,7 +56,7 @@ func (test *DifficultyTest) Run(config *params.ChainConfig) error {
 		UncleHash:  test.UncleHash,
 	}
 
-	actual := ethash.CalcDifficulty(config, test.CurrentTimestamp.Uint64(), parent)
+	actual := ethash.CalcDifficulty(config, test.CurrentTimestamp, parent)
 	exp := test.CurrentDifficulty
 
 	if actual.Cmp(exp) != 0 {
diff --git a/tests/gen_btheader.go b/tests/gen_btheader.go
index 5cfd4bd0aec0..f2e086a7b3be 100644
--- a/tests/gen_btheader.go
+++ b/tests/gen_btheader.go
@@ -14,6 +14,7 @@ import (
 
 var _ = (*btHeaderMarshaling)(nil)
 
+// MarshalJSON marshals as JSON.
 func (b btHeader) MarshalJSON() ([]byte, error) {
 	type btHeader struct {
 		Bloom            types.Bloom
@@ -31,7 +32,7 @@ func (b btHeader) MarshalJSON() ([]byte, error) {
 		Difficulty       *math.HexOrDecimal256
 		GasLimit         math.HexOrDecimal64
 		GasUsed          math.HexOrDecimal64
-		Timestamp        *math.HexOrDecimal256
+		Timestamp        math.HexOrDecimal64
 	}
 	var enc btHeader
 	enc.Bloom = b.Bloom
@@ -49,10 +50,11 @@ func (b btHeader) MarshalJSON() ([]byte, error) {
 	enc.Difficulty = (*math.HexOrDecimal256)(b.Difficulty)
 	enc.GasLimit = math.HexOrDecimal64(b.GasLimit)
 	enc.GasUsed = math.HexOrDecimal64(b.GasUsed)
-	enc.Timestamp = (*math.HexOrDecimal256)(b.Timestamp)
+	enc.Timestamp = math.HexOrDecimal64(b.Timestamp)
 	return json.Marshal(&enc)
 }
 
+// UnmarshalJSON unmarshals from JSON.
 func (b *btHeader) UnmarshalJSON(input []byte) error {
 	type btHeader struct {
 		Bloom            *types.Bloom
@@ -70,7 +72,7 @@ func (b *btHeader) UnmarshalJSON(input []byte) error {
 		Difficulty       *math.HexOrDecimal256
 		GasLimit         *math.HexOrDecimal64
 		GasUsed          *math.HexOrDecimal64
-		Timestamp        *math.HexOrDecimal256
+		Timestamp        *math.HexOrDecimal64
 	}
 	var dec btHeader
 	if err := json.Unmarshal(input, &dec); err != nil {
@@ -122,7 +124,7 @@ func (b *btHeader) UnmarshalJSON(input []byte) error {
 		b.GasUsed = uint64(*dec.GasUsed)
 	}
 	if dec.Timestamp != nil {
-		b.Timestamp = (*big.Int)(dec.Timestamp)
+		b.Timestamp = uint64(*dec.Timestamp)
 	}
 	return nil
 }
diff --git a/tests/gen_difficultytest.go b/tests/gen_difficultytest.go
index 88f36ce99957..cd15ae31b5d3 100644
--- a/tests/gen_difficultytest.go
+++ b/tests/gen_difficultytest.go
@@ -12,31 +12,33 @@ import (
 
 var _ = (*difficultyTestMarshaling)(nil)
 
+// MarshalJSON marshals as JSON.
 func (d DifficultyTest) MarshalJSON() ([]byte, error) {
 	type DifficultyTest struct {
-		ParentTimestamp    *math.HexOrDecimal256 `json:"parentTimestamp"`
+		ParentTimestamp    math.HexOrDecimal64   `json:"parentTimestamp"`
 		ParentDifficulty   *math.HexOrDecimal256 `json:"parentDifficulty"`
 		UncleHash          common.Hash           `json:"parentUncles"`
-		CurrentTimestamp   *math.HexOrDecimal256 `json:"currentTimestamp"`
+		CurrentTimestamp   math.HexOrDecimal64   `json:"currentTimestamp"`
 		CurrentBlockNumber math.HexOrDecimal64   `json:"currentBlockNumber"`
 		CurrentDifficulty  *math.HexOrDecimal256 `json:"currentDifficulty"`
 	}
 	var enc DifficultyTest
-	enc.ParentTimestamp = (*math.HexOrDecimal256)(d.ParentTimestamp)
+	enc.ParentTimestamp = math.HexOrDecimal64(d.ParentTimestamp)
 	enc.ParentDifficulty = (*math.HexOrDecimal256)(d.ParentDifficulty)
 	enc.UncleHash = d.UncleHash
-	enc.CurrentTimestamp = (*math.HexOrDecimal256)(d.CurrentTimestamp)
+	enc.CurrentTimestamp = math.HexOrDecimal64(d.CurrentTimestamp)
 	enc.CurrentBlockNumber = math.HexOrDecimal64(d.CurrentBlockNumber)
 	enc.CurrentDifficulty = (*math.HexOrDecimal256)(d.CurrentDifficulty)
 	return json.Marshal(&enc)
 }
 
+// UnmarshalJSON unmarshals from JSON.
 func (d *DifficultyTest) UnmarshalJSON(input []byte) error {
 	type DifficultyTest struct {
-		ParentTimestamp    *math.HexOrDecimal256 `json:"parentTimestamp"`
+		ParentTimestamp    *math.HexOrDecimal64  `json:"parentTimestamp"`
 		ParentDifficulty   *math.HexOrDecimal256 `json:"parentDifficulty"`
 		UncleHash          *common.Hash          `json:"parentUncles"`
-		CurrentTimestamp   *math.HexOrDecimal256 `json:"currentTimestamp"`
+		CurrentTimestamp   *math.HexOrDecimal64  `json:"currentTimestamp"`
 		CurrentBlockNumber *math.HexOrDecimal64  `json:"currentBlockNumber"`
 		CurrentDifficulty  *math.HexOrDecimal256 `json:"currentDifficulty"`
 	}
@@ -45,7 +47,7 @@ func (d *DifficultyTest) UnmarshalJSON(input []byte) error {
 		return err
 	}
 	if dec.ParentTimestamp != nil {
-		d.ParentTimestamp = (*big.Int)(dec.ParentTimestamp)
+		d.ParentTimestamp = uint64(*dec.ParentTimestamp)
 	}
 	if dec.ParentDifficulty != nil {
 		d.ParentDifficulty = (*big.Int)(dec.ParentDifficulty)
@@ -54,7 +56,7 @@ func (d *DifficultyTest) UnmarshalJSON(input []byte) error {
 		d.UncleHash = *dec.UncleHash
 	}
 	if dec.CurrentTimestamp != nil {
-		d.CurrentTimestamp = (*big.Int)(dec.CurrentTimestamp)
+		d.CurrentTimestamp = uint64(*dec.CurrentTimestamp)
 	}
 	if dec.CurrentBlockNumber != nil {
 		d.CurrentBlockNumber = uint64(*dec.CurrentBlockNumber)