diff --git a/core/blockchain.go b/core/blockchain.go
index c194ebc6bc..84652aa042 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1010,41 +1010,9 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 //
 // After insertion is done, all accumulated events will be fired.
 func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
-	if bc.chainConfig != nil && bc.chainConfig.Posv != nil {
-		epoch := bc.chainConfig.Posv.Epoch
-		gap := bc.chainConfig.Posv.Gap
-		length := len(chain)
-		start := int(chain[0].NumberU64() % epoch)
-		end := int(epoch - gap - uint64(start))
-		if (end < 0) {
-			end = end + int(epoch)
-		}
-		start = 0
-		for {
-			if end >= length {
-				end = length - 1
-			}
-			inserts := make([]*types.Block, end-start+1)
-			copy(inserts, chain[start:end+1])
-			if len(inserts) > 0 {
-				n, events, logs, err := bc.insertChain(inserts)
-				bc.PostChainEvents(events, logs)
-				if err != nil {
-					return n, err
-				}
-			}
-			start = end + 1
-			end = end + int(epoch)
-			if (start >= length) {
-				break
-			}
-		}
-		return 0, nil
-	} else {
-		n, events, logs, err := bc.insertChain(chain)
-		bc.PostChainEvents(events, logs)
-		return n, err
-	}
+	n, events, logs, err := bc.insertChain(chain)
+	bc.PostChainEvents(events, logs)
+	return n, err
 }
 
 // insertChain will execute the actual chain insertion and event aggregation. The
@@ -1224,14 +1192,14 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 		stats.processed++
 		stats.usedGas += usedGas
 		stats.report(chain, i, bc.stateCache.TrieDB().Size())
-		if bc.chainConfig.Posv != nil {
+		if i == len(chain)-1 && bc.chainConfig.Posv != nil {
 			// epoch block
 			if (chain[i].NumberU64() % bc.chainConfig.Posv.Epoch) == 0 {
 				CheckpointCh <- 1
 			}
 			// prepare set of masternodes for the next epoch
 			if (chain[i].NumberU64() % bc.chainConfig.Posv.Epoch) == (bc.chainConfig.Posv.Epoch - bc.chainConfig.Posv.Gap) {
-				bc.UpdateM1()
+				M1Ch <- 1
 			}
 		}
 	}
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index 90bbba65a5..89a274c0de 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -25,7 +25,7 @@ import (
 	"sync/atomic"
 	"time"
 
-	ethereum "github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -172,6 +172,8 @@ type LightChain interface {
 
 // BlockChain encapsulates functions required to sync a (full or fast) blockchain.
 type BlockChain interface {
+	Config() *params.ChainConfig
+	UpdateM1()
 	LightChain
 
 	// HasBlock verifies a block's presence in the local chain.
@@ -1322,11 +1324,38 @@ func (d *Downloader) processFullSyncContent() error {
 		if len(results) == 0 {
 			return nil
 		}
-		if d.chainInsertHook != nil {
-			d.chainInsertHook(results)
+		epoch := d.blockchain.Config().Posv.Epoch
+		gap := d.blockchain.Config().Posv.Gap
+		length := len(results)
+		start := int(results[0].Header.Number.Uint64() % epoch)
+		end := int(epoch - gap - uint64(start))
+		if (end < 0) {
+			end = end + int(epoch)
 		}
-		if err := d.importBlockResults(results); err != nil {
-			return err
+		start = 0
+		for {
+			if end >= length {
+				end = length - 1
+			}
+			inserts := make([]*fetchResult, end-start+1)
+			copy(inserts, results[start:end+1])
+			if len(inserts) > 0 {
+				if d.chainInsertHook != nil {
+					d.chainInsertHook(inserts)
+				}
+				if err := d.importBlockResults(inserts); err != nil {
+					return err
+				}
+				// prepare set of masternodes for the next epoch
+				if (inserts[len(inserts)-1].Header.Number.Uint64() % epoch) == (epoch - gap) {
+					d.blockchain.UpdateM1()
+				}
+			}
+			start = end + 1
+			end = end + int(epoch)
+			if (start >= length) {
+				break
+			}
 		}
 	}
 }
@@ -1355,6 +1384,7 @@ func (d *Downloader) importBlockResults(results []*fetchResult) error {
 		log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "err", err)
 		return errInvalidChain
 	}
+
 	return nil
 }
 
diff --git a/eth/downloader/downloader_test.go b/eth/downloader/downloader_test.go
index 56ce1aebd6..35dcdbc782 100644
--- a/eth/downloader/downloader_test.go
+++ b/eth/downloader/downloader_test.go
@@ -456,6 +456,10 @@ func (dl *downloadTester) dropPeer(id string) {
 	dl.downloader.UnregisterPeer(id)
 }
 
+// Config retrieves the blockchain's chain configuration.
+func (dl *downloadTester) Config() *params.ChainConfig { return dl.downloader.blockchain.Config() }
+func (dl *downloadTester) UpdateM1()                   { dl.downloader.blockchain.UpdateM1() }
+
 type downloadTesterPeer struct {
 	dl    *downloadTester
 	id    string