diff --git a/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/EnvelopeProtoMapper.kt b/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/EnvelopeProtoMapper.kt
index 7f8b2b56267..7471228ec90 100644
--- a/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/EnvelopeProtoMapper.kt
+++ b/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/EnvelopeProtoMapper.kt
@@ -18,6 +18,7 @@
 
 package com.wire.kalium.network.api.base.authenticated.message
 
+import com.wire.kalium.protobuf.otr.ClientId
 import com.wire.kalium.protobuf.otr.ClientMismatchStrategy
 import com.wire.kalium.protobuf.otr.QualifiedNewOtrMessage
 import com.wire.kalium.protobuf.otr.QualifiedUserEntry
@@ -35,8 +36,8 @@ internal class EnvelopeProtoMapperImpl : EnvelopeProtoMapper {
 
     private val otrClientEntryMapper = OtrClientEntryMapper()
     private val otrUserIdMapper = provideOtrUserIdMapper()
-    private val otrClientIdMapper = OtrClientIdMapper()
 
+    @OptIn(ExperimentalStdlibApi::class)
     override fun encodeToProtobuf(envelopeParameters: MessageApi.Parameters.QualifiedDefaultParameters): ByteArray {
         val qualifiedEntries = envelopeParameters.recipients.entries.groupBy({ it.key.domain }) { userEntry ->
             val clientEntries = userEntry.value.entries.map(otrClientEntryMapper::toOtrClientEntry)
@@ -81,7 +82,7 @@ internal class EnvelopeProtoMapperImpl : EnvelopeProtoMapper {
 
         return QualifiedNewOtrMessage(
             recipients = qualifiedEntries,
-            sender = otrClientIdMapper.toOtrClientId(envelopeParameters.sender),
+            sender = ClientId(envelopeParameters.sender.hexToLong()),
             blob = envelopeParameters.externalBlob?.let { ByteArr(it) },
             clientMismatchStrategy = strategy,
             nativePush = envelopeParameters.nativePush,
diff --git a/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientEntryMapper.kt b/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientEntryMapper.kt
index a689cdf811d..bf551473c4e 100644
--- a/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientEntryMapper.kt
+++ b/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientEntryMapper.kt
@@ -19,13 +19,14 @@
 package com.wire.kalium.network.api.base.authenticated.message
 
 import com.wire.kalium.protobuf.otr.ClientEntry
+import com.wire.kalium.protobuf.otr.ClientId
 import pbandk.ByteArr
 
 internal class OtrClientEntryMapper {
 
-    private val clientIdMapper = OtrClientIdMapper()
+    @OptIn(ExperimentalStdlibApi::class)
     fun toOtrClientEntry(clientPayload: Map.Entry<String, ByteArray>): ClientEntry = ClientEntry(
-        client = clientIdMapper.toOtrClientId(clientPayload.key),
+        client = ClientId(clientPayload.key.hexToLong()),
         text = ByteArr(clientPayload.value),
     )
 }
diff --git a/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientIdMapper.kt b/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientIdMapper.kt
deleted file mode 100644
index e3a9fdadc4c..00000000000
--- a/network/src/commonMain/kotlin/com/wire/kalium/network/api/base/authenticated/message/OtrClientIdMapper.kt
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
- * Wire
- * Copyright (C) 2023 Wire Swiss GmbH
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see http://www.gnu.org/licenses/.
- */
-
-package com.wire.kalium.network.api.base.authenticated.message
-
-import com.wire.kalium.protobuf.otr.ClientId
-
-internal class OtrClientIdMapper {
-    fun toOtrClientId(clientId: String): ClientId = ClientId(clientId.decodeHexToLong())
-}
-
-private fun String.decodeHexToLong(): Long {
-
-    @Suppress("MagicNumber")
-    fun unsignedLong(mostSignificantBits: Long, leastSignificantBits: Long) =
-        (mostSignificantBits shl 32) or leastSignificantBits
-
-    val a = this.padStart(length = 16, '0').chunked(size = 8) {
-        it.toString().toLongOrNull(radix = 16) ?: 0
-    }
-
-    return unsignedLong(a[0], a[1])
-}
diff --git a/network/src/commonTest/kotlin/com/wire/kalium/model/QualifiedSendMessageRequestJson.kt b/network/src/commonTest/kotlin/com/wire/kalium/model/QualifiedSendMessageRequestJson.kt
index 921d3398062..b05a77611d1 100644
--- a/network/src/commonTest/kotlin/com/wire/kalium/model/QualifiedSendMessageRequestJson.kt
+++ b/network/src/commonTest/kotlin/com/wire/kalium/model/QualifiedSendMessageRequestJson.kt
@@ -90,7 +90,7 @@ object QualifiedSendMessageRequestJson {
 
     val validDefaultParameters = ValidJsonProvider(
         MessageApi.Parameters.QualifiedDefaultParameters(
-            sender = "sender-client-it",
+            sender = USER_1_CLIENT_1,
             externalBlob = "blob-id".toByteArray(),
             nativePush = true,
             recipients = mapOf(),