diff --git a/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosPowScheme.scala b/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosPowScheme.scala
index db796e4b75..048928d2e1 100644
--- a/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosPowScheme.scala
+++ b/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosPowScheme.scala
@@ -240,7 +240,7 @@ class AutolykosPowScheme(val k: Int, val n: Int) extends ScorexLogging {
   /**
     * Get target `b` from encoded difficulty `nBits`
     */
-  private[mining] def getB(nBits: Long): BigInt = {
+  def getB(nBits: Long): BigInt = {
     q / DifficultySerializer.decodeCompactBits(nBits)
   }
 
@@ -363,7 +363,7 @@ class AutolykosPowScheme(val k: Int, val n: Int) extends ScorexLogging {
     * Check nonces from `startNonce` to `endNonce` for message `m`, secrets `sk` and `x`, difficulty `b`.
     * Return AutolykosSolution if there is any valid nonce in this interval.
     */
-  private[mining] def checkNonces(version: Header.Version,
+  def checkNonces(version: Header.Version,
                                   h: Array[Byte],
                                   m: Array[Byte],
                                   sk: BigInt,
diff --git a/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosSolution.scala b/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosSolution.scala
index cf745e685b..e75412828e 100644
--- a/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosSolution.scala
+++ b/ergo-core/src/main/scala/org/ergoplatform/mining/AutolykosSolution.scala
@@ -128,6 +128,10 @@ object AutolykosSolutionSerializer {
     serializer(blockVersion).serialize(solution, w)
   }
 
+  def toBytes(blockVersion: Version, solution: AutolykosSolution): Array[Byte] = {
+    serializer(blockVersion).toBytes(solution)
+  }
+
   def parse(r: Reader, blockVersion: Version): AutolykosSolution = {
     serializer(blockVersion).parse(r)
   }
diff --git a/ergo-core/src/main/scala/org/ergoplatform/modifiers/history/header/Header.scala b/ergo-core/src/main/scala/org/ergoplatform/modifiers/history/header/Header.scala
index 092dcd219f..28a7ab1a51 100644
--- a/ergo-core/src/main/scala/org/ergoplatform/modifiers/history/header/Header.scala
+++ b/ergo-core/src/main/scala/org/ergoplatform/modifiers/history/header/Header.scala
@@ -56,7 +56,7 @@ case class Header(override val version: Header.Version,
                   override val sizeOpt: Option[Int] = None) extends HeaderWithoutPow(version, parentId, ADProofsRoot, stateRoot, transactionsRoot, timestamp,
   nBits, height, extensionRoot, votes) with PreHeader with BlockSection {
 
-  override def serializedId: Array[Header.Version] = Algos.hash(bytes)
+  override def serializedId: Array[Byte] = Algos.hash(bytes)
 
   override type M = Header
 
diff --git a/src/test/scala/org/ergoplatform/modifiers/history/HeadersSpec.scala b/src/test/scala/org/ergoplatform/modifiers/history/HeadersSpec.scala
index e802139257..d824790887 100644
--- a/src/test/scala/org/ergoplatform/modifiers/history/HeadersSpec.scala
+++ b/src/test/scala/org/ergoplatform/modifiers/history/HeadersSpec.scala
@@ -1,7 +1,11 @@
 package org.ergoplatform.modifiers.history
 
-import com.google.common.primitives.Longs
+import com.google.common.primitives.{Ints, Longs}
+import org.ergoplatform.mining.{AutolykosPowScheme, AutolykosSolutionSerializer, randomSecret}
+import org.ergoplatform.mining.difficulty.DifficultySerializer
+import org.ergoplatform.modifiers.history.header.{Header, HeaderSerializer}
 import org.ergoplatform.utils.ErgoCorePropertyTest
+import org.ergoplatform.utils.ErgoCoreTestConstants.powScheme
 import scorex.crypto.hash.Blake2b256
 import scorex.util.ModifierId
 
@@ -34,4 +38,30 @@ class HeadersSpec extends ErgoCorePropertyTest {
     }
   }
 
+  property("bytes can be added to the header") {
+    val pow = new AutolykosPowScheme(powScheme.k, powScheme.n)
+
+    val difficulty = 10
+    val ver = (Header.Interpreter50Version + 1).toByte
+    val nBits = DifficultySerializer.encodeCompactBits(difficulty)
+    val header = defaultHeaderGen.sample.get.copy(version = ver, nBits = nBits)
+    val bytesWithoutPow = HeaderSerializer.bytesWithoutPow(header)
+    bytesWithoutPow(bytesWithoutPow.length - 1) = 5
+    val updByteWithoutPow: Array[Byte] = bytesWithoutPow ++ Array.fill(5)(5.toByte)
+    val msg = Blake2b256(updByteWithoutPow)
+
+    val sk = randomSecret()
+    val x = randomSecret()
+    val b = pow.getB(header.nBits)
+    val hbs = Ints.toByteArray(header.height)
+    val N = pow.calcN(header)
+    val solution = pow.checkNonces(ver, hbs, msg, sk, x, b, N, 0, 1000).get
+
+    require(pow.hitForVersion2ForMessage(msg, solution.n, hbs, N) < b)
+
+    require(HeaderSerializer.parseBytesTry(updByteWithoutPow ++ AutolykosSolutionSerializer.toBytes(ver, solution)).isSuccess)
+
+    // todo: but unparsed bytes are not stored in Header, so roundtrip is broken
+  }
+
 }