diff --git a/blockmanager.go b/blockmanager.go
index 67f1a80f..b793698c 100644
--- a/blockmanager.go
+++ b/blockmanager.go
@@ -43,6 +43,7 @@ type blockManager struct {
 	shutdown          bool
 	blockChain        *btcchain.BlockChain
 	blockPeer         map[btcwire.ShaHash]*peer
+	blockPeerMutex    sync.Mutex
 	receivedLogBlocks int64
 	receivedLogTx     int64
 	lastBlockLogTime  time.Time
@@ -208,13 +209,17 @@ func (b *blockManager) handleBlockMsg(bmsg *blockMsg) {
 	// Keep track of which peer the block was sent from so the notification
 	// handler can request the parent blocks from the appropriate peer.
 	blockSha, _ := bmsg.block.Sha()
+	b.blockPeerMutex.Lock()
 	b.blockPeer[*blockSha] = bmsg.peer
+	b.blockPeerMutex.Unlock()
 
 	// Process the block to include validation, best chain selection, orphan
 	// handling, etc.
 	err := b.blockChain.ProcessBlock(bmsg.block)
 	if err != nil {
+		b.blockPeerMutex.Lock()
 		delete(b.blockPeer, *blockSha)
+		b.blockPeerMutex.Unlock()
 		log.Warnf("[BMGR] Failed to process block %v: %v", blockSha, err)
 		return
 	}
@@ -222,7 +227,9 @@ func (b *blockManager) handleBlockMsg(bmsg *blockMsg) {
 	// Don't keep track of the peer that sent the block any longer if it's
 	// not an orphan.
 	if !b.blockChain.IsKnownOrphan(blockSha) {
+		b.blockPeerMutex.Lock()
 		delete(b.blockPeer, *blockSha)
+		b.blockPeerMutex.Unlock()
 	}
 
 	// Log info about the new block height.
@@ -271,6 +278,9 @@ func (b *blockManager) handleNotifyMsg(notification *btcchain.Notification) {
 	switch notification.Type {
 	// An orphan block has been accepted by the block chain.
 	case btcchain.NTOrphanBlock:
+		b.blockPeerMutex.Lock()
+		defer b.blockPeerMutex.Unlock()
+
 		orphanHash := notification.Data.(*btcwire.ShaHash)
 		if peer, exists := b.blockPeer[*orphanHash]; exists {
 			orphanRoot := b.blockChain.GetOrphanRoot(orphanHash)