diff --git a/hive_integration/nodocker/consensus/consensus_sim.nim b/hive_integration/nodocker/consensus/consensus_sim.nim
index 24d38d5e7..6cf509e97 100644
--- a/hive_integration/nodocker/consensus/consensus_sim.nim
+++ b/hive_integration/nodocker/consensus/consensus_sim.nim
@@ -8,8 +8,8 @@
 # those terms.
 
 import
-  std/[os, parseopt, json],
-  eth/[common, p2p, trie/db], stew/byteutils,
+  std/[os, parseopt, strformat, json],
+  eth/[common, trie/db], stew/byteutils,
   ../../../nimbus/db/db_chain,
   ../../../nimbus/[genesis, config, conf_utils],
   ../sim_utils
@@ -42,7 +42,13 @@ proc main() =
                    else:
                      paramStr(1)
 
+  if not caseFolder.dirExists:
+    # Handy early error message and stop directive
+    let progname = getAppFilename().extractFilename
+    quit(&"*** {progname}: Not a case folder: {caseFolder}")
+
   runTest("Consensus", caseFolder):
+    # Variable `fileName` is injected by `runTest()`
     let node = parseFile(fileName)
     processNode(fileName, node["chainfile"].getStr,
       node["lastblockhash"].getStr, testStatusIMPL)
diff --git a/nimbus/conf_utils.nim b/nimbus/conf_utils.nim
index 98692b166..ab2aa090c 100644
--- a/nimbus/conf_utils.nim
+++ b/nimbus/conf_utils.nim
@@ -19,7 +19,7 @@ type
   EthHeader = object
     header: BlockHeader
 
-proc importRlpBlock*(importFile: string, chainDB: BasechainDB): bool =
+proc importRlpBlock*(importFile: string; chainDB: BasechainDB): bool =
   let res = io2.readAllBytes(importFile)
   if res.isErr:
     error "failed to import", fileName = importFile
diff --git a/nimbus/p2p/chain.nim b/nimbus/p2p/chain.nim
index b0dce3f0f..7d7fc2c7b 100644
--- a/nimbus/p2p/chain.nim
+++ b/nimbus/p2p/chain.nim
@@ -1,7 +1,17 @@
-import ../db/db_chain, eth/common, chronicles, ../vm_state,
-  stint, nimcrypto,
-  ../utils, eth/trie/db, ./executor, ../chain_config, ../genesis, ../utils,
-  stew/endians2, ./validate, ./validate/epoch_hash_cache
+import
+  ../chain_config,
+  ../db/db_chain,
+  ../genesis,
+  ../utils,
+  ../vm_state,
+  ./executor,
+  ./validate,
+  ./validate/epoch_hash_cache,
+  chronicles,
+  eth/[common, trie/db],
+  nimcrypto,
+  stew/endians2,
+  stint
 
 when not defined(release):
   import ../tracer
@@ -130,7 +140,8 @@ method getAncestorHeader*(c: Chain, h: BlockHeader, output: var BlockHeader, ski
 method getBlockBody*(c: Chain, blockHash: KeccakHash): BlockBodyRef =
   result = nil
 
-method persistBlocks*(c: Chain, headers: openarray[BlockHeader], bodies: openarray[BlockBody]): ValidationResult {.gcsafe.} =
+method persistBlocks*(c: Chain; headers: openarray[BlockHeader];
+                  bodies: openarray[BlockBody]): ValidationResult {.gcsafe.} =
   # Run the VM here
   if headers.len != bodies.len:
     debug "Number of headers not matching number of bodies"
@@ -140,11 +151,15 @@ method persistBlocks*(c: Chain, headers: openarray[BlockHeader], bodies: openarr
   let transaction = c.db.db.beginTransaction()
   defer: transaction.dispose()
 
-  trace "Persisting blocks", fromBlock = headers[0].blockNumber, toBlock = headers[^1].blockNumber
+  trace "Persisting blocks",
+    fromBlock = headers[0].blockNumber,
+    toBlock = headers[^1].blockNumber
+
   for i in 0 ..< headers.len:
-    let head = c.db.getCanonicalHead()
-    let vmState = newBaseVMState(head.stateRoot, headers[i], c.db)
-    let validationResult = processBlock(c.db, headers[i], bodies[i], vmState)
+    let
+      head = c.db.getBlockHeader(headers[i].parentHash)
+      vmState = newBaseVMState(head.stateRoot, headers[i], c.db)
+      validationResult = processBlock(c.db, headers[i], bodies[i], vmState)
 
     when not defined(release):
       if validationResult == ValidationResult.Error and
@@ -167,10 +182,6 @@ method persistBlocks*(c: Chain, headers: openarray[BlockHeader], bodies: openarr
         return ValidationResult.Error
 
     discard c.db.persistHeaderToDb(headers[i])
-    if c.db.getCanonicalHead().blockHash != headers[i].blockHash:
-      debug "Stored block header hash doesn't match declared hash"
-      return ValidationResult.Error
-
     discard c.db.persistTransactions(headers[i].blockNumber, bodies[i].transactions)
     discard c.db.persistReceipts(vmState.receipts)