diff --git a/sdk/src/androidTest/java/network/xyo/client/NodeClientTest.kt b/sdk/src/androidTest/java/network/xyo/client/NodeClientTest.kt
index b4aaaed..f648600 100644
--- a/sdk/src/androidTest/java/network/xyo/client/NodeClientTest.kt
+++ b/sdk/src/androidTest/java/network/xyo/client/NodeClientTest.kt
@@ -1,11 +1,14 @@
 package network.xyo.client
 
+import android.content.Context
+import androidx.test.platform.app.InstrumentationRegistry
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.runBlocking
 import network.xyo.client.account.Account
 import network.xyo.client.archivist.wrapper.ArchivistWrapper
 import network.xyo.client.node.client.NodeClient
 import network.xyo.client.payload.XyoPayload
+import org.junit.Before
 import org.junit.Test
 import org.junit.jupiter.api.Assertions.*
 
@@ -16,15 +19,23 @@ class DiscoverPayload(): XyoPayload() {
 class NodeClientTest {
     private val apiDomainBeta = "${TestConstants.nodeUrlBeta}/Archivist"
 
+    private lateinit var appContext: Context
+
+    @Before
+    fun useAppContext() {
+        // Context of the app under test.
+        this.appContext = InstrumentationRegistry.getInstrumentation().targetContext
+    }
+
     @OptIn(ExperimentalCoroutinesApi::class)
     @Test
     fun discoverTestBeta() {
         val account = Account.random()
-        val client = NodeClient(TestConstants.nodeUrlBeta, account)
+        val client = NodeClient(TestConstants.nodeUrlBeta, account, appContext)
         val query = DiscoverPayload()
 
         runBlocking {
-            val postResult = client.query(query, null, null)
+            val postResult = client.query(query, null)
             assertEquals(null, postResult.errors)
         }
     }
@@ -46,12 +57,12 @@ class NodeClientTest {
 
     @Test
     fun archivistInsertTest() {
-        val archivist = ArchivistWrapper(NodeClient(apiDomainBeta, TestConstants.TestAccount))
+        val archivist = ArchivistWrapper(NodeClient(apiDomainBeta, TestConstants.TestAccount, appContext))
 
         val payloads = arrayListOf(TestConstants.debugPayload)
 
         runBlocking {
-            val (response, errors) = archivist.insert(payloads, null)
+            val (response, errors) = archivist.insert(payloads)
             assertNotEquals(response, null)
             assertEquals(errors, null)
 
@@ -63,7 +74,7 @@ class NodeClientTest {
         }
 
         runBlocking {
-            val getResult = archivist.get(arrayListOf(TestConstants.debugPayloadHash), null)
+            val getResult = archivist.get(arrayListOf(TestConstants.debugPayloadHash))
             assertNotEquals(getResult.response, null)
 
             val response = getResult.response
diff --git a/sdk/src/androidTest/java/network/xyo/client/XyoBoundWitnessTest.kt b/sdk/src/androidTest/java/network/xyo/client/XyoBoundWitnessTest.kt
index cc71685..6cfed49 100644
--- a/sdk/src/androidTest/java/network/xyo/client/XyoBoundWitnessTest.kt
+++ b/sdk/src/androidTest/java/network/xyo/client/XyoBoundWitnessTest.kt
@@ -7,6 +7,7 @@ import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.runBlocking
 import network.xyo.client.account.Account
 import network.xyo.client.boundwitness.XyoBoundWitnessBuilder
+import network.xyo.client.datastore.previous_hash_store.PreviousHashStorePrefsRepository
 import network.xyo.client.node.client.NodeClient
 import network.xyo.client.payload.XyoPayload
 import org.junit.Before
@@ -34,9 +35,14 @@ class XyoBoundWitnessTest {
         this.appContext = InstrumentationRegistry.getInstrumentation().targetContext
     }
 
+    @Before
+    fun setupAccount() {
+        Account.previousHashStore = PreviousHashStorePrefsRepository.getInstance(InstrumentationRegistry.getInstrumentation().targetContext)
+    }
+
     fun generateQuery(nodeUrl: String): RequestDependencies {
         val account = Account.random()
-        val client = NodeClient(nodeUrl, account)
+        val client = NodeClient(nodeUrl, account, appContext)
         val query = DiscoverPayload()
         val payloads = mutableListOf<XyoPayload>()
         payloads.add(TestPayload1())
@@ -47,7 +53,7 @@ class XyoBoundWitnessTest {
     fun testSendQueryBW(nodeUrl: String) {
         runBlocking {
             val(client, query, payloads) = generateQuery(nodeUrl)
-            val postResult = client.query(query, payloads, null)
+            val postResult = client.query(query, payloads)
             assertEquals(null, postResult.errors)
         }
     }
@@ -66,11 +72,21 @@ class XyoBoundWitnessTest {
     @Test
     fun testBoundWitnessHash() {
         runBlocking {
-            val bw = XyoBoundWitnessBuilder().signer(Account.random()).payloads(listOf(TestPayload1())).build()
+            val bw = XyoBoundWitnessBuilder(appContext).signer(Account.random()).payloads(listOf(TestPayload1())).build()
             val hashableFields = bw.getBodyJson()
             assert(bw._hash !== null)
             assert(bw._hash!! == XyoSerializable.sha256String(hashableFields))
             assert(bw._hash!! == hashableFields.hash())
         }
     }
+
+    @Test
+    fun testBoundWitnessPreviousHash() {
+        runBlocking {
+            val testAccount = Account.random()
+            val bw = XyoBoundWitnessBuilder(appContext).signer(testAccount).payloads(listOf(TestPayload1())).build()
+            val bw2 = XyoBoundWitnessBuilder(appContext).signer(testAccount).payloads(listOf(TestPayload1())).build()
+            assert(bw2.previous_hashes.contains(bw._hash))
+        }
+    }
 }
\ No newline at end of file
diff --git a/sdk/src/androidTest/java/network/xyo/client/XyoPanelTest.kt b/sdk/src/androidTest/java/network/xyo/client/XyoPanelTest.kt
index 8e98967..c03445f 100644
--- a/sdk/src/androidTest/java/network/xyo/client/XyoPanelTest.kt
+++ b/sdk/src/androidTest/java/network/xyo/client/XyoPanelTest.kt
@@ -65,7 +65,7 @@ class XyoPanelTest {
         runBlocking {
             val witnessAccount = Account.fromPrivateKey("9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08")
             val witness2Account = Account.fromPrivateKey("5a95531488b4d0d3645aea49678297ae9e2034879ce0389b80eb788e8b533592")
-            val witness = XyoWitness(witnessAccount, fun(_: Context, _: String?): List<XyoPayload> {
+            val witness = XyoWitness(witnessAccount, fun(_: Context): List<XyoPayload> {
                 return listOf(BasicPayload())
             })
             val panel = XyoPanel(appContext, Account.random(), arrayListOf(Pair(nodeUrl, Account.random())), listOf(witness, XyoSystemInfoWitness(witness2Account), XyoLocationWitness()))
@@ -94,7 +94,7 @@ class XyoPanelTest {
     @Test
     fun testSimplePanelReport() {
         runBlocking {
-            val panel = XyoPanel(appContext, Account.random(), fun(_:Context, _: String?): List<XyoEventPayload> {
+            val panel = XyoPanel(appContext, Account.random(), fun(_:Context): List<XyoEventPayload> {
                 return listOf(XyoEventPayload("test_event"))
             })
             val result = panel.reportAsyncQuery()
diff --git a/sdk/src/androidTest/java/network/xyo/client/XyoPayloadTest.kt b/sdk/src/androidTest/java/network/xyo/client/XyoPayloadTest.kt
index 483506c..d97ffa8 100644
--- a/sdk/src/androidTest/java/network/xyo/client/XyoPayloadTest.kt
+++ b/sdk/src/androidTest/java/network/xyo/client/XyoPayloadTest.kt
@@ -93,14 +93,14 @@ class XyoPayloadTest {
     @Test
     fun testRoundTripPanel() {
         val address = Account.fromPrivateKey("5a95531488b4d0d3645aea49678297ae9e2034879ce0389b80eb788e8b533592")
-        val witness = XyoWitness(address, fun(_: Context, _: String?): List<XyoPayload> {
+        val witness = XyoWitness(address, fun(_: Context): List<XyoPayload> {
             return listOf(BasicPayload())
         })
 
         CoroutineScope(Dispatchers.Main).launch {
             val response = arrayListOf(witness.observe(appContext))
             val payloads = response.mapNotNull { payload -> payload }.flatten()
-            val bwJson = XyoBoundWitnessBuilder()
+            val bwJson = XyoBoundWitnessBuilder(appContext)
                 .payloads(payloads)
                 .signer(Account.random())
                 .build()
diff --git a/sdk/src/androidTest/java/network/xyo/client/prefs/AccountPrefsRepositoryTest.kt b/sdk/src/androidTest/java/network/xyo/client/prefs/AccountPrefsRepositoryTest.kt
index 91b8f2e..752e8f0 100644
--- a/sdk/src/androidTest/java/network/xyo/client/prefs/AccountPrefsRepositoryTest.kt
+++ b/sdk/src/androidTest/java/network/xyo/client/prefs/AccountPrefsRepositoryTest.kt
@@ -131,7 +131,7 @@ class AccountPrefsRepositoryTest {
             assertEquals(firstAccount.privateKey.toHexString(), testAccount.privateKey.toHexString())
 
             // Sign with the test account
-            val firstBw = XyoBoundWitnessBuilder().signer(firstAccount).payloads(listOf(
+            val firstBw = XyoBoundWitnessBuilder(appContext).signer(firstAccount).payloads(listOf(
                 TestConstants.debugPayload
             )).build()
             val firstAddress = firstBw.addresses.first()
@@ -141,7 +141,7 @@ class AccountPrefsRepositoryTest {
             val secondAccount = secondInstance.getAccount()
 
             // Sign with the test account
-            val secondBw = XyoBoundWitnessBuilder().signer(secondAccount).payloads(listOf(
+            val secondBw = XyoBoundWitnessBuilder(appContext).signer(secondAccount).payloads(listOf(
                 TestConstants.debugPayload
             )).build()
             val secondAddress = secondBw.addresses.first()
diff --git a/sdk/src/main/java/network/xyo/client/XyoPanel.kt b/sdk/src/main/java/network/xyo/client/XyoPanel.kt
index 23c793a..21c3e21 100644
--- a/sdk/src/main/java/network/xyo/client/XyoPanel.kt
+++ b/sdk/src/main/java/network/xyo/client/XyoPanel.kt
@@ -29,7 +29,6 @@ class XyoPanel(
     private val witnesses: List<XyoWitness<XyoPayload>>?,
     private val nodeUrlsAndAccounts: ArrayList<Pair<String, AccountInstance?>>?
 ) {
-    var previousHash: String? = null
     private var nodes: MutableList<NodeClient>? = null
     var defaultAccount: AccountInstance? = null
 
@@ -80,7 +79,7 @@ class XyoPanel(
     constructor(
         context: Context,
         account: AccountInstance,
-        observe: ((context: Context, previousHash: String?) -> List<XyoEventPayload>?)?
+        observe: ((context: Context) -> List<XyoEventPayload>?)?
     ): this(
         context,
         account,
@@ -96,7 +95,7 @@ class XyoPanel(
                 this@XyoPanel.nodeUrlsAndAccounts.forEach { pair ->
                     val nodeUrl = pair.first
                     val account = pair.second ?: defaultAccount
-                    it.add(NodeClient(nodeUrl, account))
+                    it.add(NodeClient(nodeUrl, account, context))
                 }
                 it
             }
@@ -114,7 +113,7 @@ class XyoPanel(
     suspend fun eventAsync(event: String): XyoPanelReportResult {
         val adhocWitnessList = listOf(
             XyoWitness({
-                _, previousHash -> listOf(XyoEventPayload(event))
+                _, -> listOf(XyoEventPayload(event))
             })
         )
         return this.reportAsync(adhocWitnessList)
@@ -124,7 +123,7 @@ class XyoPanel(
     suspend fun eventAsyncQuery(event: String): XyoPanelReportQueryResult {
         val adhocWitnessList = listOf(
             XyoWitness({
-                    _, previousHash -> listOf(XyoEventPayload(event))
+                    _, -> listOf(XyoEventPayload(event))
             })
         )
         return reportAsyncQuery(adhocWitnessList)
@@ -147,10 +146,10 @@ class XyoPanel(
     private suspend fun generateBoundWitnessJson(adhocWitnesses: List<XyoWitness<XyoPayload>> = emptyList()): XyoBoundWitnessJson {
         val witnesses: List<XyoWitness<XyoPayload>> = (this.witnesses ?: emptyList()).plus(adhocWitnesses)
         val payloads = generatePayloads()
-        return XyoBoundWitnessBuilder()
+        return XyoBoundWitnessBuilder(context)
             .payloads(payloads)
             .signer(account)
-            .build(previousHash)
+            .build()
     }
 
 
@@ -167,7 +166,6 @@ class XyoPanel(
     @kotlinx.coroutines.ExperimentalCoroutinesApi
     suspend fun reportAsync(adhocWitnesses: List<XyoWitness<XyoPayload>> = emptyList()): XyoPanelReportResult {
         val bw = generateBoundWitnessJson(adhocWitnesses)
-        previousHash = bw._hash
         val results = mutableListOf<PostBoundWitnessesResult>()
         archivists?.forEach { archivist ->
             results.add(archivist.postBoundWitnessAsync(bw))
@@ -179,7 +177,6 @@ class XyoPanel(
     suspend fun reportAsyncQuery(adhocWitnesses: List<XyoWitness<XyoPayload>> = emptyList()): XyoPanelReportQueryResult {
         if (nodes == null) resolveNodes()
         val bw = generateBoundWitnessJson()
-        previousHash = bw._hash
         val payloads = generatePayloads(adhocWitnesses)
         val results = mutableListOf<PostQueryResult>()
 
@@ -190,7 +187,7 @@ class XyoPanel(
         nodes?.forEach { node ->
             val archivist = ArchivistWrapper(node)
             val payloadsWithBoundWitness = payloads.plus(bw)
-            val queryResult = archivist.insert(payloadsWithBoundWitness, previousHash)
+            val queryResult = archivist.insert(payloadsWithBoundWitness)
             results.add(queryResult)
         }
         return XyoPanelReportQueryResult(bw, results, payloads)
diff --git a/sdk/src/main/java/network/xyo/client/XyoWitness.kt b/sdk/src/main/java/network/xyo/client/XyoWitness.kt
index af39317..59050d7 100644
--- a/sdk/src/main/java/network/xyo/client/XyoWitness.kt
+++ b/sdk/src/main/java/network/xyo/client/XyoWitness.kt
@@ -8,37 +8,34 @@ import network.xyo.client.account.model.AccountInstance
 import network.xyo.client.payload.XyoPayload
 
 abstract class DeferredObserver<out T: XyoPayload> {
-    abstract suspend fun deferredDetect(context: Context, previousHash: String?): List<T>?
+    abstract suspend fun deferredDetect(context: Context): List<T>?
 }
 
 @RequiresApi(Build.VERSION_CODES.M)
 open class XyoWitness<out T: XyoPayload> (
     val address: AccountInstance = Account.random(),
-    private val observer: ((context: Context, previousHash: String) -> List<T>?)? = null,
-    var previousHash: String = "",
+    private val observer: ((context: Context) -> List<T>?)? = null,
     val deferredObserver: DeferredObserver<T>? = null
 ) {
 
     constructor(
-        observer: ((context: Context, previousHash: String) -> List<T>?)?,
-        previousHash: String = "",
+        observer: ((context: Context) -> List<T>?)?,
         account: AccountInstance = Account.random()
-    ): this(account, observer, previousHash, null)
+    ): this(account, observer)
 
     constructor(
         observer: DeferredObserver<T>?,
-        previousHash: String = "",
         account: AccountInstance = Account.random()
-    ): this(account, null, previousHash, observer)
+    ): this(account, null, observer)
 
     open suspend fun observe(context: Context): List<T>? {
         val appContext = context.applicationContext
         if (deferredObserver !== null) {
-            val payload = deferredObserver.deferredDetect(appContext, previousHash)
+            val payload = deferredObserver.deferredDetect(appContext)
             return payload
         }
         observer?.let {
-            val payloads = it(appContext, previousHash)
+            val payloads = it(appContext)
             return payloads
         }
         return null
diff --git a/sdk/src/main/java/network/xyo/client/archivist/wrapper/ArchivistWrapper.kt b/sdk/src/main/java/network/xyo/client/archivist/wrapper/ArchivistWrapper.kt
index 05e311d..c92710a 100644
--- a/sdk/src/main/java/network/xyo/client/archivist/wrapper/ArchivistWrapper.kt
+++ b/sdk/src/main/java/network/xyo/client/archivist/wrapper/ArchivistWrapper.kt
@@ -10,15 +10,15 @@ import network.xyo.client.payload.XyoPayload
 open class ArchivistWrapper(private val nodeClient: NodeClient) {
     @OptIn(ExperimentalCoroutinesApi::class)
     @RequiresApi(Build.VERSION_CODES.M)
-    suspend fun get(hashes: List<String>, previousHash: String?): PostQueryResult {
+    suspend fun get(hashes: List<String>): PostQueryResult {
         val query = ArchivistGetQueryPayload(hashes)
-        return nodeClient.query(query, null, previousHash)
+        return nodeClient.query(query, null)
     }
 
     @OptIn(ExperimentalCoroutinesApi::class)
     @RequiresApi(Build.VERSION_CODES.M)
-    suspend fun insert(payloads: List<XyoPayload>, previousHash: String?): PostQueryResult {
+    suspend fun insert(payloads: List<XyoPayload>): PostQueryResult {
         val query = ArchivistInsertQueryPayload()
-        return nodeClient.query(query, payloads, previousHash)
+        return nodeClient.query(query, payloads)
     }
 }
\ No newline at end of file
diff --git a/sdk/src/main/java/network/xyo/client/boundwitness/QueryBoundWitnessBuilder.kt b/sdk/src/main/java/network/xyo/client/boundwitness/QueryBoundWitnessBuilder.kt
index 1dd2925..d485e65 100644
--- a/sdk/src/main/java/network/xyo/client/boundwitness/QueryBoundWitnessBuilder.kt
+++ b/sdk/src/main/java/network/xyo/client/boundwitness/QueryBoundWitnessBuilder.kt
@@ -1,5 +1,6 @@
 package network.xyo.client.boundwitness
 
+import android.content.Context
 import android.os.Build
 import androidx.annotation.RequiresApi
 import network.xyo.client.XyoSerializable
@@ -8,7 +9,7 @@ import network.xyo.client.payload.XyoPayload
 
 
 @RequiresApi(Build.VERSION_CODES.M)
-class QueryBoundWitnessBuilder : XyoBoundWitnessBuilder() {
+class QueryBoundWitnessBuilder(context: Context) : XyoBoundWitnessBuilder(context) {
     private lateinit var queryHash: String
 
     fun query(query: XyoPayload): QueryBoundWitnessBuilder {
@@ -27,13 +28,12 @@ class QueryBoundWitnessBuilder : XyoBoundWitnessBuilder() {
         return this
     }
 
-    override suspend fun build(previousHash: String?): QueryBoundWitnessJson {
+    override suspend fun build(): QueryBoundWitnessJson {
         bw = QueryBoundWitnessJson()
         // override to support additional properties for query bound witnesses
         return bw.let {
             val qbw = it as QueryBoundWitnessJson
             qbw.query = this.queryHash
-            qbw._previous_hash = previousHash
             constructFields()
             it
         }
diff --git a/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessBuilder.kt b/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessBuilder.kt
index b2c978b..f5bfd63 100644
--- a/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessBuilder.kt
+++ b/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessBuilder.kt
@@ -1,15 +1,17 @@
 package network.xyo.client.boundwitness
 
+import android.content.Context
 import android.os.Build
 import androidx.annotation.RequiresApi
 import network.xyo.client.XyoSerializable
 import network.xyo.client.account.hexStringToByteArray
 import network.xyo.client.account.model.AccountInstance
+import network.xyo.client.datastore.previous_hash_store.PreviousHashStorePrefsRepository
 import network.xyo.client.payload.XyoPayload
 import network.xyo.client.payload.XyoValidationException
 
 @RequiresApi(Build.VERSION_CODES.M)
-open class XyoBoundWitnessBuilder {
+open class XyoBoundWitnessBuilder(private val context: Context) {
     protected var _signers = mutableListOf<AccountInstance>()
     protected var _payload_hashes = mutableListOf<String>()
     protected var _payload_schemas = mutableListOf<String>()
@@ -32,10 +34,16 @@ open class XyoBoundWitnessBuilder {
         return this
     }
 
-    private fun hashableFields(): XyoBoundWitnessBodyJson {
+    @OptIn(ExperimentalStdlibApi::class)
+    private suspend fun hashableFields(): XyoBoundWitnessBodyJson {
         // if a timestamp is not provided, set one at the time hashable fields are set
         bw.timestamp = _timestamp ?: System.currentTimeMillis()
 
+        bw.previous_hashes = addresses.map {
+            val store = PreviousHashStorePrefsRepository.getInstance(context)
+            store.getItem(hexStringToByteArray(it))?.toHexString()
+        }
+
         // return the body with hashable fields
         return bw.getBodyJson()
     }
@@ -88,11 +96,8 @@ open class XyoBoundWitnessBuilder {
         bw._hash = hash
     }
 
-    open suspend fun build(previousHash: String? = null): XyoBoundWitnessJson {
+    open suspend fun build(): XyoBoundWitnessJson {
         return bw.let{
-            // store the previous hash on the class
-            it._previous_hash = previousHash
-
             // update fields
             constructFields()
             it
diff --git a/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessJson.kt b/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessJson.kt
index 2392da7..4fda7ac 100644
--- a/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessJson.kt
+++ b/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessJson.kt
@@ -6,7 +6,6 @@ import com.squareup.moshi.JsonClass
 open class XyoBoundWitnessJson: XyoBoundWitnessBodyJson(), XyoBoundWitnessMetaInterface {
     override var _signatures: List<String>? = null
     override var _client: String? = null
-    override var _previous_hash: String? = null
     override var _hash: String? = null
 
     open fun getBodyJson(): XyoBoundWitnessBodyJson {
diff --git a/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessMetaInterface.kt b/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessMetaInterface.kt
index 37aa55a..4efdfd9 100644
--- a/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessMetaInterface.kt
+++ b/sdk/src/main/java/network/xyo/client/boundwitness/XyoBoundWitnessMetaInterface.kt
@@ -6,5 +6,4 @@ interface XyoBoundWitnessMetaInterface : Payload {
     var _hash: String?
     var _signatures: List<String>?
     var _client: String?
-    var _previous_hash: String?
 }
\ No newline at end of file
diff --git a/sdk/src/main/java/network/xyo/client/node/client/NodeClient.kt b/sdk/src/main/java/network/xyo/client/node/client/NodeClient.kt
index d5c0188..648a0f6 100644
--- a/sdk/src/main/java/network/xyo/client/node/client/NodeClient.kt
+++ b/sdk/src/main/java/network/xyo/client/node/client/NodeClient.kt
@@ -1,5 +1,6 @@
 package network.xyo.client.node.client
 
+import android.content.Context
 import android.os.Build
 import android.util.Log
 import androidx.annotation.RequiresApi
@@ -22,8 +23,7 @@ import org.json.JSONObject
 import java.io.IOException
 
 @RequiresApi(Build.VERSION_CODES.M)
-class NodeClient(private val url: String, private val accountToUse: AccountInstance?) {
-
+class NodeClient(private val url: String, private val accountToUse: AccountInstance?, private val context: Context) {
     private val _internalAccount = Account.random()
     private val okHttp = OkHttpClient()
 
@@ -39,8 +39,8 @@ class NodeClient(private val url: String, private val accountToUse: AccountInsta
 
     @ExperimentalCoroutinesApi
     @RequiresApi(Build.VERSION_CODES.M)
-    suspend fun query(query: XyoPayload, payloads: List<XyoPayload>?, previousHash: String?): PostQueryResult {
-        val bodyString = buildQuery(query, payloads, previousHash)
+    suspend fun query(query: XyoPayload, payloads: List<XyoPayload>?): PostQueryResult {
+        val bodyString = buildQuery(query, payloads)
         val postBody = bodyString.toRequestBody(MEDIA_TYPE_JSON)
         val request = Request.Builder()
             .url(url)
@@ -81,20 +81,20 @@ class NodeClient(private val url: String, private val accountToUse: AccountInsta
     }
 
     @RequiresApi(Build.VERSION_CODES.M)
-    private suspend fun buildQuery(query: XyoPayload, payloads: List<XyoPayload>?, previousHash: String?): String {
-        val builtQuery = queryBuilder(query, payloads, previousHash)
+    private suspend fun buildQuery(query: XyoPayload, payloads: List<XyoPayload>?): String {
+        val builtQuery = queryBuilder(query, payloads)
         val queryPayloads = buildQueryPayloads(query, payloads)
         val queryPayloadsJsonArray = queryPayloadsJsonArray(queryPayloads)
         val builtQueryTuple = arrayListOf(XyoSerializable.toJson((builtQuery)), queryPayloadsJsonArray.toString())
         return builtQueryTuple.joinToString(",", "[", "]")
     }
 
-    private suspend fun queryBuilder(query: XyoPayload, payloads: List<XyoPayload>?, previousHash: String?): QueryBoundWitnessJson {
-        return QueryBoundWitnessBuilder().let {
+    private suspend fun queryBuilder(query: XyoPayload, payloads: List<XyoPayload>?): QueryBoundWitnessJson {
+        return QueryBoundWitnessBuilder(context).let {
             payloads?.let { payload ->
                 it.payloads(payload)
             }
-            it.signer(this.account).query(query).build(previousHash)
+            it.signer(this.account).query(query).build()
 
         }
     }
diff --git a/sdk/src/main/java/network/xyo/client/witness/location/info/XyoLocationWitness.kt b/sdk/src/main/java/network/xyo/client/witness/location/info/XyoLocationWitness.kt
index 53d381f..f06f05e 100644
--- a/sdk/src/main/java/network/xyo/client/witness/location/info/XyoLocationWitness.kt
+++ b/sdk/src/main/java/network/xyo/client/witness/location/info/XyoLocationWitness.kt
@@ -12,7 +12,6 @@ import network.xyo.client.account.model.AccountInstance
 class DeferredLocationObserver : DeferredObserver<XyoLocationPayload>() {
     override suspend fun deferredDetect(
         context: Context,
-        previousHash: String?
     ): List<XyoLocationPayload>? {
         try {
             return listOf(XyoLocationPayload.detect(context))
@@ -26,6 +25,5 @@ class DeferredLocationObserver : DeferredObserver<XyoLocationPayload>() {
 @RequiresApi(Build.VERSION_CODES.M)
 class XyoLocationWitness(address: AccountInstance = Account.random()) : XyoWitness<XyoLocationPayload>(
     DeferredLocationObserver(),
-    "",
     address
-    )
\ No newline at end of file
+)
\ No newline at end of file
diff --git a/sdk/src/main/java/network/xyo/client/witness/system/info/XyoSystemInfoWitness.kt b/sdk/src/main/java/network/xyo/client/witness/system/info/XyoSystemInfoWitness.kt
index 0a1d762..1193cee 100644
--- a/sdk/src/main/java/network/xyo/client/witness/system/info/XyoSystemInfoWitness.kt
+++ b/sdk/src/main/java/network/xyo/client/witness/system/info/XyoSystemInfoWitness.kt
@@ -9,9 +9,8 @@ import network.xyo.client.account.model.AccountInstance
 
 @RequiresApi(Build.VERSION_CODES.M)
 class XyoSystemInfoWitness(address: AccountInstance = Account.random()) : XyoWitness<XyoSystemInfoPayload>(
-    fun (context: Context, _: String?): List<XyoSystemInfoPayload> {
+    fun (context: Context): List<XyoSystemInfoPayload> {
         return listOf(XyoSystemInfoPayload.detect(context))
     },
-    "",
     address
 )
\ No newline at end of file