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 b203ed5..d97ffa8 100644
--- a/sdk/src/androidTest/java/network/xyo/client/XyoPayloadTest.kt
+++ b/sdk/src/androidTest/java/network/xyo/client/XyoPayloadTest.kt
@@ -93,7 +93,7 @@ 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())
         })
 
diff --git a/sdk/src/main/java/network/xyo/client/XyoPanel.kt b/sdk/src/main/java/network/xyo/client/XyoPanel.kt
index 1c9a537..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,
@@ -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)
@@ -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>()
 
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/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