diff --git a/beacon_chain/networking/eth2_network.nim b/beacon_chain/networking/eth2_network.nim
index ea9e2125e..2a630d451 100644
--- a/beacon_chain/networking/eth2_network.nim
+++ b/beacon_chain/networking/eth2_network.nim
@@ -614,6 +614,12 @@ when useNativeSnappy:
 else:
   include libp2p_streams_backend
 
+func maxChunkSize(t: typedesc[bellatrix.SignedBeaconBlock]): uint32 =
+  MAX_CHUNK_SIZE_BELLATRIX
+
+func maxChunkSize(t: typedesc): uint32 =
+  MAX_CHUNK_SIZE
+
 proc makeEth2Request(peer: Peer, protocolId: string, requestBytes: Bytes,
                      ResponseMsg: type,
                      timeout: Duration): Future[NetRes[ResponseMsg]]
@@ -635,7 +641,7 @@ proc makeEth2Request(peer: Peer, protocolId: string, requestBytes: Bytes,
     # Read the response
     return
       await readResponse(when useNativeSnappy: libp2pInput(stream) else: stream,
-                         peer, ResponseMsg, timeout)
+                         peer, maxChunkSize(ResponseMsg), ResponseMsg, timeout)
   finally:
     await stream.closeWithEOF()
 
@@ -787,8 +793,10 @@ proc handleIncomingStream(network: Eth2Node,
       NetRes[MsgRec].ok default(MsgRec)
     else:
       try:
-        awaitWithTimeout(readChunkPayload(s, peer, MsgRec), deadline):
-          returnInvalidRequest(errorMsgLit "Request full data not sent in time")
+        awaitWithTimeout(
+          readChunkPayload(s, peer, maxChunkSize(MsgRec), MsgRec), deadline):
+            returnInvalidRequest(
+              errorMsgLit "Request full data not sent in time")
 
       except SerializationError as err:
         returnInvalidRequest err.formatMsg("msg")
@@ -1963,7 +1971,7 @@ template gossipMaxSize(T: untyped): uint32 =
          T is altair.SignedBeaconBlock:
       GOSSIP_MAX_SIZE
     else:
-      {.fatal: "unknown type".}
+      {.fatal: "unknown type " & name(T).}
   static: doAssert maxSize <= maxGossipMaxSize()
   maxSize.uint32
 
diff --git a/beacon_chain/networking/faststreams_backend.nim b/beacon_chain/networking/faststreams_backend.nim
index 6a465b4ee..1cc188e18 100644
--- a/beacon_chain/networking/faststreams_backend.nim
+++ b/beacon_chain/networking/faststreams_backend.nim
@@ -86,6 +86,8 @@ proc readSszValue(s: AsyncInputStream,
 proc readChunkPayload(s: AsyncInputStream,
                       noSnappy: bool,
                       MsgType: type): Future[NetRes[MsgType]] {.async.} =
+  # TODO this needs to sometimes be MAX_CHUNK_SIZE_BELLATRIX, for at least
+  # bellatrix.SignedBeaconBlock
   let prefix = await readSizePrefix(s, MAX_CHUNK_SIZE)
   let size = if prefix.isOk: prefix.value.int
              else: return err(prefix.error)
diff --git a/beacon_chain/networking/libp2p_streams_backend.nim b/beacon_chain/networking/libp2p_streams_backend.nim
index f0f318bbf..116fb397e 100644
--- a/beacon_chain/networking/libp2p_streams_backend.nim
+++ b/beacon_chain/networking/libp2p_streams_backend.nim
@@ -99,6 +99,7 @@ proc uncompressFramedStream*(conn: Connection,
   return ok output
 
 proc readChunkPayload*(conn: Connection, peer: Peer,
+                       maxChunkSize: uint32,
                        MsgType: type): Future[NetRes[MsgType]] {.async.} =
   let sm = now(chronos.Moment)
   let size =
@@ -112,7 +113,7 @@ proc readChunkPayload*(conn: Connection, peer: Peer,
     except InvalidVarintError:
       return neterr UnexpectedEOF
 
-  if size > MAX_CHUNK_SIZE:
+  if size > maxChunkSize:
     return neterr SizePrefixOverflow
   if size == 0:
     return neterr ZeroSizePrefix
@@ -129,7 +130,7 @@ proc readChunkPayload*(conn: Connection, peer: Peer,
     debug "Snappy decompression/read failed", msg = $data.error, conn
     return neterr InvalidSnappyBytes
 
-proc readResponseChunk(conn: Connection, peer: Peer,
+proc readResponseChunk(conn: Connection, peer: Peer, maxChunkSize: uint32,
                        MsgType: typedesc): Future[NetRes[MsgType]] {.async.} =
   mixin readChunkPayload
 
@@ -148,7 +149,8 @@ proc readResponseChunk(conn: Connection, peer: Peer,
     case responseCode:
     of InvalidRequest, ServerError, ResourceUnavailable:
       let
-        errorMsgChunk = await readChunkPayload(conn, peer, ErrorMsg)
+        errorMsgChunk = await readChunkPayload(
+          conn, peer, maxChunkSize, ErrorMsg)
         errorMsg = if errorMsgChunk.isOk: errorMsgChunk.value
                    else: return err(errorMsgChunk.error)
         errorMsgStr = toPrettyString(errorMsg.asSeq)
@@ -159,12 +161,12 @@ proc readResponseChunk(conn: Connection, peer: Peer,
     of Success:
       discard
 
-    return await readChunkPayload(conn, peer, MsgType)
+    return await readChunkPayload(conn, peer, maxChunkSize, MsgType)
 
   except LPStreamEOFError, LPStreamIncompleteError:
     return neterr UnexpectedEOF
 
-proc readResponse(conn: Connection, peer: Peer,
+proc readResponse(conn: Connection, peer: Peer, maxChunkSize: uint32,
                   MsgType: type, timeout: Duration): Future[NetRes[MsgType]] {.async.} =
   when MsgType is seq:
     type E = ElemType(MsgType)
@@ -176,7 +178,7 @@ proc readResponse(conn: Connection, peer: Peer,
       # The problem is exacerbated by the large number of round-trips to the
       # poll loop that each future along the way causes.
       trace "reading chunk", conn
-      let nextFut = conn.readResponseChunk(peer, E)
+      let nextFut = conn.readResponseChunk(peer, maxChunkSize, E)
       if not await nextFut.withTimeout(timeout):
         return neterr(ReadResponseTimeout)
       let nextRes = nextFut.read()
@@ -192,7 +194,7 @@ proc readResponse(conn: Connection, peer: Peer,
         trace "Got chunk", conn
         results.add nextRes.value
   else:
-    let nextFut = conn.readResponseChunk(peer, MsgType)
+    let nextFut = conn.readResponseChunk(peer, maxChunkSize, MsgType)
     if not await nextFut.withTimeout(timeout):
       return neterr(ReadResponseTimeout)
     return nextFut.read()
diff --git a/beacon_chain/spec/keystore.nim b/beacon_chain/spec/keystore.nim
index 6a834dffc..0b8cb20b8 100644
--- a/beacon_chain/spec/keystore.nim
+++ b/beacon_chain/spec/keystore.nim
@@ -29,7 +29,7 @@ import nimcrypto/utils as ncrutils
 export
   results, burnMem, writeValue, readValue
 
-{.localPassC: "-fno-lto".} # no LTO for crypto
+{.localPassc: "-fno-lto".} # no LTO for crypto
 
 type
   KeystoreMode* = enum
diff --git a/beacon_chain/sync/sync_protocol.nim b/beacon_chain/sync/sync_protocol.nim
index baa881b4c..e62fe0e20 100644
--- a/beacon_chain/sync/sync_protocol.nim
+++ b/beacon_chain/sync/sync_protocol.nim
@@ -70,7 +70,8 @@ type
   BlockRootsList* = List[Eth2Digest, Limit MAX_REQUEST_BLOCKS]
 
 proc readChunkPayload*(
-    conn: Connection, peer: Peer, MsgType: type (ref ForkedSignedBeaconBlock)):
+    conn: Connection, peer: Peer, maxChunkSize: uint32,
+    MsgType: type (ref ForkedSignedBeaconBlock)):
     Future[NetRes[MsgType]] {.async.} =
   var contextBytes: ForkDigest
   try:
@@ -78,20 +79,25 @@ proc readChunkPayload*(
   except CatchableError:
     return neterr UnexpectedEOF
 
+  # Ignores maxChunkSize; needs to be consistent formal parameters,
+  # but this function is where that's determined.
   if contextBytes == peer.network.forkDigests.phase0:
-    let res = await readChunkPayload(conn, peer, phase0.SignedBeaconBlock)
+    let res = await readChunkPayload(
+      conn, peer, MAX_CHUNK_SIZE, phase0.SignedBeaconBlock)
     if res.isOk:
       return ok newClone(ForkedSignedBeaconBlock.init(res.get))
     else:
       return err(res.error)
   elif contextBytes == peer.network.forkDigests.altair:
-    let res = await readChunkPayload(conn, peer, altair.SignedBeaconBlock)
+    let res = await readChunkPayload(
+      conn, peer, MAX_CHUNK_SIZE, altair.SignedBeaconBlock)
     if res.isOk:
       return ok newClone(ForkedSignedBeaconBlock.init(res.get))
     else:
       return err(res.error)
   elif contextBytes == peer.network.forkDigests.bellatrix:
-    let res = await readChunkPayload(conn, peer, bellatrix.SignedBeaconBlock)
+    let res = await readChunkPayload(
+      conn, peer, MAX_CHUNK_SIZE_BELLATRIX, bellatrix.SignedBeaconBlock)
     if res.isOk:
       return ok newClone(ForkedSignedBeaconBlock.init(res.get))
     else:
diff --git a/beacon_chain/validators/keystore_management.nim b/beacon_chain/validators/keystore_management.nim
index 0b98c4487..1d49a8ffc 100644
--- a/beacon_chain/validators/keystore_management.nim
+++ b/beacon_chain/validators/keystore_management.nim
@@ -26,7 +26,7 @@ export
 when defined(windows):
   import stew/[windows/acl]
 
-{.localPassC: "-fno-lto".} # no LTO for crypto
+{.localPassc: "-fno-lto".} # no LTO for crypto
 
 const
   KeystoreFileName* = "keystore.json"
diff --git a/config.nims b/config.nims
index b4db5d9b2..023fb1b01 100644
--- a/config.nims
+++ b/config.nims
@@ -181,7 +181,7 @@ switch("warning", "LockLevel:off")
 # ############################################################
 
 # This applies per-file compiler flags to C files
-# which do not support {.localPassC: "-fno-lto".}
+# which do not support {.localPassc: "-fno-lto".}
 # Unfortunately this is filename based instead of path-based
 # Assumes GCC