diff --git a/chain/blocksync/client.go b/chain/blocksync/client.go
index 3164d45bf..cf67b4802 100644
--- a/chain/blocksync/client.go
+++ b/chain/blocksync/client.go
@@ -23,7 +23,7 @@ import (
 
 // Protocol client.
 // FIXME: Rename to just `Client`. Not done at the moment to avoid
-//  disrupt too much of the consumer code, should be done along
+//  disrupting too much of the consumer code, should be done along
 //  https://github.com/filecoin-project/lotus/issues/2612.
 type BlockSync struct {
 	// Connection manager used to contact the server.
@@ -53,7 +53,7 @@ func NewClient(
 // either a response error status, a failed validation or an internal
 // error.
 //
-// This is the internal single-point-of-entry for all external-facing
+// This is the internal single point of entry for all external-facing
 // APIs, currently we have 3 very heterogeneous services exposed:
 // * GetBlocks:         Headers
 // * GetFullTipSet:     Headers | Messages
@@ -67,21 +67,21 @@ func (client *BlockSync) doRequest(
 	req *Request,
 	singlePeer *peer.ID,
 ) (*validatedResponse, error) {
-		// Validate request.
-		if req.Length == 0 {
-			return nil, xerrors.Errorf("invalid request of length 0")
-		}
-		if req.Length > MaxRequestLength {
-			return nil, xerrors.Errorf("request length (%d) above maximum (%d)",
-				req.Length, MaxRequestLength)
-		}
-		if req.Options == 0 {
-			return nil, xerrors.Errorf("request with no options set")
-		}
+	// Validate request.
+	if req.Length == 0 {
+		return nil, xerrors.Errorf("invalid request of length 0")
+	}
+	if req.Length > MaxRequestLength {
+		return nil, xerrors.Errorf("request length (%d) above maximum (%d)",
+			req.Length, MaxRequestLength)
+	}
+	if req.Options == 0 {
+		return nil, xerrors.Errorf("request with no options set")
+	}
 
-		// Generate the list of peers to be queried, either the
-		// `singlePeer` indicated or all peers available (sorted
-		// by an internal peer tracker with some randomness injected).
+	// Generate the list of peers to be queried, either the
+	// `singlePeer` indicated or all peers available (sorted
+	// by an internal peer tracker with some randomness injected).
 	var peers []peer.ID
 	if singlePeer != nil {
 		peers = []peer.ID{*singlePeer}
@@ -130,16 +130,15 @@ func (client *BlockSync) doRequest(
 
 	errString := "doRequest failed for all peers"
 	if singlePeer != nil {
-		errString = "doRequest failed for single peer"
-		// (The peer has already been logged before, don't print it again.)
+		errString = fmt.Sprintf("doRequest failed for single peer %s", *singlePeer)
 	}
 	return nil, xerrors.Errorf(errString)
 }
 
-// Process and validate response. Check the status and that the information
-// returned matches the request (and its integrity). Extract the information
+// Process and validate response. Check the status, the integrity of the
+// information returned, and that it matches the request. Extract the information
 // into a `validatedResponse` for the external-facing APIs to select what they
-// want.
+// need.
 //
 // We are conflating in the single error returned both status and validation
 // errors. Peer penalization should happen here then, before returning, so
@@ -156,8 +155,8 @@ func (client *BlockSync) processResponse(
 
 	options := parseOptions(req.Options)
 	if options.noOptionsSet() {
-		// Safety check, this shouldn't happen, and even if it did
-		// it should be caught by the peer in its error status.
+		// Safety check: this shouldn't have been sent, and even if it did
+		// it should have been caught by the peer in its error status.
 		return nil, xerrors.Errorf("nothing was requested")
 	}
 
@@ -191,7 +190,7 @@ func (client *BlockSync) processResponse(
 			return nil, xerrors.Errorf("returned chain head does not match request")
 		}
 
-		// Check `TipSet` are connected (valid chain).
+		// Check `TipSet`s are connected (valid chain).
 		for i := 0; i < len(validRes.tipsets) - 1; i++ {
 			if validRes.tipsets[i].IsChildOf(validRes.tipsets[i+1]) == false {
 				return nil, fmt.Errorf("tipsets are not connected at height (head - %d)/(head - %d)",
@@ -382,6 +381,7 @@ func (client *BlockSync) sendRequestToPeer(
 		// FIXME: What's the point of setting a blank deadline that won't time out?
 		//  Is this our way of clearing the old one?
 		client.peerTracker.logFailure(peer, build.Clock.Since(connectionStart))
+		// FIXME: Should we also remove peer here?
 		return nil, err
 	}
 	// FIXME: Same, why are we doing this again here?
@@ -390,7 +390,6 @@ func (client *BlockSync) sendRequestToPeer(
 	// Read response.
 	var res Response
 	err = cborutil.ReadCborRPC(
-		// FIXME: Extract constants.
 		bufio.NewReader(incrt.New(stream, READ_RES_MIN_SPEED, READ_RES_DEADLINE)),
 		&res)
 	if err != nil {
@@ -423,7 +422,7 @@ func (client *BlockSync) RemovePeer(p peer.ID) {
 // getShuffledPeers returns a preference-sorted set of peers (by latency
 // and failure counting), shuffling the first few peers so we don't always
 // pick the same peer.
-// FIXME: Merge with the shuffle if we *always* do it.
+// FIXME: Consider merging with `shufflePrefix()s`.
 func (client *BlockSync) getShuffledPeers() []peer.ID {
 	peers := client.peerTracker.prefSortedPeers()
 	shufflePrefix(peers)