diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt
index e77fcdb08e..0bf293eca4 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt
@@ -30,7 +30,7 @@ import io.element.android.features.roomcall.api.aStandByCallState
 import io.element.android.libraries.designsystem.components.avatar.AvatarData
 import io.element.android.libraries.designsystem.components.avatar.AvatarSize
 import io.element.android.libraries.designsystem.preview.ROOM_NAME
-import io.element.android.libraries.designsystem.preview.USER_NAME_ALICE
+import io.element.android.libraries.designsystem.preview.USER_NAME_SENDER
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UniqueId
@@ -145,7 +145,7 @@ internal fun aTimelineItemEvent(
     isMine: Boolean = false,
     isEditable: Boolean = false,
     canBeRepliedTo: Boolean = false,
-    senderDisplayName: String = USER_NAME_ALICE,
+    senderDisplayName: String = USER_NAME_SENDER,
     displayNameAmbiguous: Boolean = false,
     content: TimelineItemEventContent = aTimelineItemTextContent(),
     groupPosition: TimelineItemGroupPosition = TimelineItemGroupPosition.None,
@@ -162,7 +162,7 @@ internal fun aTimelineItemEvent(
         eventId = eventId,
         transactionId = transactionId,
         senderId = UserId("@senderId:domain"),
-        senderAvatar = AvatarData("@senderId:domain", "sender", size = AvatarSize.TimelineSender),
+        senderAvatar = AvatarData("@senderId:domain", USER_NAME_SENDER, size = AvatarSize.TimelineSender),
         content = content,
         reactionsState = timelineItemReactions,
         readReceiptState = readReceiptState,
diff --git a/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/PreviewData.kt b/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/PreviewData.kt
index f728cce302..66a6043634 100644
--- a/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/PreviewData.kt
+++ b/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/PreviewData.kt
@@ -16,6 +16,7 @@ const val USER_NAME_EVE = "Eve"
 const val USER_NAME_JOHN_DOE = "John Doe"
 const val USER_NAME_JUSTIN = "Justin"
 const val USER_NAME_MALLORY = "Mallory"
+const val USER_NAME_SENDER = "Sender"
 const val USER_NAME_SUSIE = "Susie"
 const val USER_NAME_VICTOR = "Victor"
 const val USER_NAME_WALTER = "Walter"
diff --git a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/MatrixUserProvider.kt b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/MatrixUserProvider.kt
index 84a226edc7..1b662ad7c1 100644
--- a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/MatrixUserProvider.kt
+++ b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/MatrixUserProvider.kt
@@ -44,7 +44,7 @@ fun aMatrixUser(
     displayName: String? = USER_NAME_ALICE,
     avatarUrl: String? = null,
 ) = MatrixUser(
-    userId = UserId(id ?: "@${displayName?.lowercase() ?: "id_of_alice"}:server.org"),
+    userId = UserId(id ?: "@${displayName?.lowercase()?.replace(" ", "_") ?: "id_of_alice"}:server.org"),
     displayName = displayName,
     avatarUrl = avatarUrl,
 )
diff --git a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/reply/InReplyToDetailsProvider.kt b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/reply/InReplyToDetailsProvider.kt
index b66beb009c..ca118349e9 100644
--- a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/reply/InReplyToDetailsProvider.kt
+++ b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/reply/InReplyToDetailsProvider.kt
@@ -9,7 +9,7 @@
 package io.element.android.libraries.matrix.ui.messages.reply
 
 import androidx.compose.ui.tooling.preview.PreviewParameterProvider
-import io.element.android.libraries.designsystem.preview.USER_NAME_ALICE
+import io.element.android.libraries.designsystem.preview.USER_NAME_SENDER
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.media.MediaSource
@@ -160,7 +160,7 @@ private fun aInReplyToDetails(
 )
 
 fun aProfileDetailsReady(
-    displayName: String? = USER_NAME_ALICE,
+    displayName: String? = USER_NAME_SENDER,
     displayNameAmbiguous: Boolean = false,
     avatarUrl: String? = null,
 ) = ProfileDetails.Ready(